Temperature control using time proportional output of a heater

A temperature control unit according to one or more embodiments may include an acquisition unit that is configured to acquire an operation amount from a controller, and an SSR control unit that is configured to perform time proportional output of an instruction to drive or stop a heater to SSR after reflecting the operation amount.

TECHNICAL FIELD

The present invention relates to an output control unit that performs output control of an output apparatus according to information from a control apparatus.

RELATED ART

Conventionally, in the field of factory automation (FA), a system configuration is adopted in which a controller such as a PLC (programmable logic controller) controls various input/output units such that the input/output units exchange data with input/output apparatuses.FIG. 7is a diagram showing an outline of a conventional output control system.FIG. 7shows a system in which a heater is used to control the temperature of a target object, as an example. As illustrated, a controller transmits various instructions or various types of information to various units, and the various units collect data from an input/output apparatus (e.g., a temperature sensor).

RELATED ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

Incidentally, in a system that performs temperature control as shown inFIG. 7, a heater, which is an example of an output apparatus is connected to a digital output unit via an SSR. In addition, the digital output unit, which is an example of various units is connected to a controller via a network. In such a system, temperature control is performed by the digital output unit turning on and off the heater via the SSR in accordance with time proportional output (TPO) from the controller. Here, “time proportional output” refers to an output method for proportionally changing an ON/OFF time ratio as output.

A conventional controller as shown inFIG. 7sets a value indicating an ON/OFF time ratio of an output apparatus as a setting value, and causes the apparatus to which the controller belongs to calculate on and off times of the output apparatus that are derived from the setting value and a predetermined control cycle of the above-described TPO. More specifically, a configuration has been adopted in which a user program for calculating on and off times of the output apparatus based on the value indicating an ON/OFF time ratio of the output apparatus and the value of the control cycle of the above-described TPO is stored in the controller in advance, and the controller executes the user program. Note that the user program is created according to a control purpose of the user. The controller has then output, to various units, either information including an instruction to turn on the output apparatus or information including an instruction to turn off the output apparatus, according to the calculated times.

However, if such a communication system is adopted for apparatuses, there has been a risk that there are deviations of TPO depending on the cycle time of a controller and a TPO control cycle. In the following description, for simplification, the control cycle of the controller and the communication cycle of the network are synchronized.FIGS. 8A to 8Care diagrams showing the relationship between a setting value that is set by a controller and the value of an instruction to turn on or off an output apparatus (output value) that is actually output by the controller to various units, in a conventional output control system.FIG. 8Ais a diagram showing an ideal relationship between a setting value and an output value. It is ideal that an ON/OFF time ratio indicated by the output value matches the setting value as illustrated. In addition, if the apparatus to which the controller belongs changes the setting value, it is desirable that the controller adjusts the output value to the various units as well such that the changed setting value can be realized. For example, if the setting value is changed from 50% to 5% as illustrated, it is ideal that the controller sets the output value to ON for the period of 5% of one TPO control cycle in various units, and sets the output value to OFF for the 95% remaining time.

However, if setting value is set without taking the relationship between the cycle time of the controller itself and the TPO control cycle of the various units into consideration, there is a risk that ideal output control as shown inFIG. 8Acannot be realized. For example, if the setting value is set such that a time during which the output apparatus is driven in one TPO control cycle is shorter than the cycle time of the controller, the setting value and the output value do not match. For example, if the setting value is 5%, and the TPO control cycle is 2 seconds(s), then the controller should set the output value to ON for 0.1 s, and set the output value to OFF for 1.9 s.

However, if the cycle time of the controller is 0.5 s as shown inFIG. 8B, then the minimum time unit by which the controller can change the output value is 0.5 s. Therefore, for example, even if the setting value is set to 5%, it is not possible to realize control in which the output value is ON for the period of 0.1 s as described above. As a result, as shown inFIG. 8B, the output value is on for the period of 0.5 s, and is OFF for the remaining period of 1.5 s.

In addition, also if a time during which the output apparatus is to be driven in one TPO control cycle is indivisible by the cycle time of the controller, the setting value and the output value do not match. For example, as shown inFIG. 8C, if the TPO control cycle is 2 s, the cycle time of the controller is 0.6 s, and the setting value is 50%, the controller can switch the output value only in units of 0.6 s. Therefore, as illustrated, the ON/OFF ratio of output determined by the setting value cannot be realized.

The invention has been made in light of the above-described problem, and aims to reduce TPO deviation due to a cycle time of a controller.

Means for Solving the Problems

In order to solve the above-described issue, an output control unit according to the invention includes an acquisition unit that acquires, from a control apparatus, an operation amount for a switching apparatus that switches between driving and stopping of an output apparatus, and an instruction output unit that performs time proportional output to the switching apparatus based on the operation amount acquired by the acquisition unit.

Also, in order to solve the above-described issue, a control method of an output control unit according to the invention includes an acquisition step of acquiring, from a control apparatus, an operation amount for a switching apparatus that switches between driving and stopping of an output apparatus and an instruction output step of performing time proportional output to the switching apparatus based on the operation amount acquired in the acquisition step.

Effects of the Invention

The invention has an effect of eliminating deviation of TPO due to a cycle time of a controller.

EMBODIMENTS OF THE INVENTION

First Embodiment

A first embodiment of the invention will be described below with reference toFIGS. 1 to 4. To begin with, an output control system100according to this embodiment will be described with reference toFIGS. 1 and 2.

Apparatuses Included in System and their Connection

The output control system100is a system for adjusting the temperature of a certain target object (e.g., a resin or water), and is a system for detecting whether or not a heater, a cooling apparatus, or the like that is used for temperature adjustment is properly driven or stopped. To begin with, apparatuses (units) included in the output control system100and their connection will be described with reference toFIG. 2.FIG. 2is a diagram showing an outline of the output control system100. The output control system100includes at least a controller (control apparatus)2, a temperature control unit (output control unit)3, a heater (output apparatus)7, an SSR (solid state relay, switching apparatus)8, and a CT (current transformer, measurement apparatus)9. The output control system100may also include a programmable display device1, a temperature input unit4, and a temperature sensor5, which are not necessary constituent elements.

As illustrated, the controller2is connected to the programmable display device1, the temperature control unit3, and the temperature input unit4via a communication coupler using a field network. Also, the temperature control unit3is connected to the controller2, the SSR8, and the CT9. In addition, the temperature input unit4is connected to the controller2and the temperature sensor5. Furthermore, the SSR8, the CT9, and the heater7are connected to each other along with a heater power supply using an electric wire.

Main Configuration of Each Apparatus

Next, actions of the apparatuses (units) will be described with reference toFIG. 1.FIG. 1is a block diagram showing a main configuration of the apparatuses and units included in the output control system100.

Programmable Display Device1

The programmable display device1is an HMI (human machine interface) that outputs, from the terminal thereof, data and notifications received from the controller2(displays data and notifications on a display unit, or outputs sound such as an alarm), and thereby presents the data and notifications to the user. Note that a configuration may also be adopted in which the programmable display device1has an input unit, and the input unit transmits an instruction received from the user to the controller2.

The controller2is a PLC (programmable logic controller) that receives data blocks circulating around a communication network that is a field network (hereinafter, simply referred to as “communication network”), adds various types of data in the data blocks, and returns the data blocks including the various types of data to the above-noted communication network. Here, “data block” refers to a collection of data that circulates (is exchanged periodically) between various devices connected to the communication network. The cycle of circulation of the data blocks is determined according to the cycle time of the controller2.

The temperature control unit3connected to the communication network receives the data blocks, and reads various types of data, which will be described later in detail. In addition, the controller2reads various types of data included in the data blocks by the temperature control unit3and the temperature input unit4. More specifically, the controller2includes a first communication unit21, a storage unit22, a second communication unit23, and a control unit20.

The first communication unit21performs communication between the controller2and the programmable display device1. Upon receiving various types of data and warnings from the control unit20, the first communication unit21transmits the data and warnings to the programmable display device1. In addition, upon receiving a user instruction from the programmable display device1, the first communication unit21transmits the user instruction to the control unit20.

The storage unit22stores user programs. Here, “user program” is a program that specifies various operations and settings of the controller2. A user program is generated by a setting tool (application) and the like installed in a general-purpose computer or the like, is downloaded to the controller2connected to the general-purpose computer, and is stored in the storage unit22. For example, a user program may include a program that specifies the times when the heater7should be driven or stopped. A user program is read out and executed by the control unit20.

The second communication unit23performs communication between the controller2, the temperature control unit3, and the temperature input unit4. The second communication unit23adds, in a data block, information indicating a control instruction generated by the control unit20, or information indicating the values of various parameters related to control and the like, and returns the data block to the communication network. The temperature control unit3connected to the communication network acquires the information by receiving the data block.

In addition, if the data block includes a warning from the temperature control unit3that the heater7is disconnected (hereinafter, simply referred to as “warning”), the second communication unit23transmits the warning to the control unit20. Also, if the data block includes temperature data (information indicating the temperature of an object that is subject to temperature adjustment) from the temperature input unit4, the second communication unit23transmits the temperature data to the control unit20.

The control unit20performs the overall control of the controller2. The control unit20generates information regarding temperature adjustment (e.g., a control instruction or various parameters) by executing a user program read out from the storage unit22, or using a method determined in advance for the apparatus in which the control unit20is included. Here, the “information regarding temperature adjustment” is information that is output by the controller2, and is information that specifies driving and stopping of the heater7. The control unit20outputs generated information via the second communication unit23. Note that the control unit20may also adjust the content of the above information, for example, degrees of driving and stopping of the heater7based on temperature data acquired by reading the data included in a data block.

Temperature Control Unit3

The temperature control unit3is a unit that gives an instruction to the SSR8according to information from the controller2, through time proportional output (TPO). The temperature control unit3is also a unit that determines, based on the content of an instruction transmitted to the SSR8and a current value acquired from the CT9, whether or not the heater7is disconnected, and if it is determined that the heater7is disconnected, transmits a warning to the controller2. More specifically, the temperature control unit3includes an acquisition unit30, an SSR control unit (instruction output unit)32, a current value acquisition unit (measured value acquisition unit)33, a determination unit34, and a warning output unit35.

The acquisition unit30acquires information from the controller2, and transmits the information to the SSR control unit32. The acquisition unit30may also acquire a warning event cancellation instruction (an instruction to cancel a warning to be described later) from the controller2. If a warning event cancellation instruction is acquired, the acquisition unit30transmits the cancellation instruction to the warning output unit35.

The SSR control unit32transmits an instruction to drive or stop the heater7to the SSR8in accordance with information acquired from the acquisition unit30. Here, an instruction to drive the heater7and an instruction to stop the heater7are output using TPO. The current value acquisition unit33acquires, from the CT9, the value of a current (current value) that is flowing in the heater7at the timing when the SSR control unit32transmits an instruction to the SSR8, and transmits the current value to the determination unit34.

The determination unit34determines, based on the content of an instruction (a driving instruction or a stop instruction) transmitted to the SSR8and the current value, whether or not the heater7is being driven and stopped according to the instruction, or whether or not the heater7is disconnected. More specifically, if the instruction transmitted to the SSR8is an instruction to drive the heater7, and the current value acquired from the current value acquisition unit33is smaller than or equal to a predetermined disconnection determination threshold (a first threshold), the determination unit34determines that the heater7is disconnected. Note that the disconnection determination threshold is a value that is lower than a lower limit value of a current value when the heater7is being driven, and may be determined as appropriate. If it is determined that the heater7is disconnected, the determination unit34transmits the determination result to the warning output unit35.

Upon receiving, from the determination unit34, the result of the determination that the heater7is disconnected, the warning output unit35generates a warning, and outputs the warning to the controller2. The warning that is output by the warning output unit35may be information to be handled as one kind of monitoring information by the controller2(monitoring information warning). The warning that is output by the warning output unit35may also be a warning (minor fault) that continues until some warning cancellation instruction is received from the controller2.

The SSR8is a circuit for controlling start and stop (ON and OFF) of the heater7. The SSR8drives or stops the heater7according to a driving instruction or a stop instruction received from the SSR control unit32of the temperature control unit3. The CT9measures the value of a current that flows in the heater7. In other words, it can be said that the CT9measures an actual operation of the heater7. The CT9may directly measure the current that flows in the heater7, or may indirectly measure the current that flows in the heater7. The CT9transmits the measurement result to the current value acquisition unit33of the temperature control unit3. The heater7warms an object such as a resin or water that is subject to temperature control. The configuration of the heater7is not limited as long as the heater7is electrically driven and can transfer heat to a target object.

Temperature Sensor5and Temperature Input Unit

The temperature sensor5measures the temperature of an object that is subject to temperature control, and transmits the temperature to the temperature input unit4. The temperature input unit4outputs temperature data indicating the temperature to the controller2.

In the examples inFIGS. 1 and 2, the determination unit34is configured to determine whether or not one apparatus, namely the heater7is disconnected. However, in the output control system100according to the invention, a configuration may also be adopted in which the determination unit34determines whether or not each of a plurality of apparatuses are disconnected, and the warning output unit35may output, to the controller2, a warning that makes it possible to distinguish which apparatus is disconnected.

To be more specific, for example, assuming that the output control system100has a plurality of electric circuits that are each constituted by an SSR8, a CT9, and a heater7(and a heater power supply) as shown inFIG. 2, the SSR control unit32gives driving or stopping instructions individually to the plurality of SSRs. The current value acquisition unit33then acquires the individual values of the currents flowing in the heaters that are switched between driving and stopping by the SSRs, from CTs that are respectively connected to the heaters, and the determination unit34performs disconnection determination for each of the heaters. The warning output unit35then outputs different warnings for the different heaters. This makes it possible to individually detect disconnection of a plurality of heaters, and give warnings.

Method for Determining Heater Disconnection

Next, the determination that is performed by the determination unit34will be described more specifically with reference toFIGS. 3A and 3B.FIG. 3Ais a timing chart showing the temporal change of input/output parameters in the temperature control unit3.

The graph “instruction output” indicates timings of instruction output from the SSR control unit32to the SSR8and the change of the instruction. “ON” represents an instruction to drive the heater7, and “OFF” represents an instruction to stop the heater7. The graph “CT current value” indicates the change in a current value that is acquired by the current value acquisition unit33from the CT9. Here, “current value during shutoff” refers to a current value when the heater7is being stopped. On the other hand, “current value during conduction” refers to a current value when the heater7is being driven. In addition, as described above, the “disconnection determination threshold” is a value that is lower than the lower limit value of a current value when the heater7is being driven, and is determined as appropriate.

The graph “warning (monitoring information)” and the graph “warning (minor fault)” each show a timing when the warning output unit35outputs a warning. The graph “warning (monitoring information)” indicates a case where a monitoring information warning is output, and the graph “warning (minor fault)” indicates a case where a minor fault warning is output.

The graph “event cancellation” indicates a timing when the acquisition unit30acquires a warning event cancellation instruction from the controller2if the warning output unit35outputs a minor fault warning. Note that, if a monitoring information warning is output, a cancellation instruction as shown in this graph is not acquired.

As described above, the SSR control unit32transmits a driving instruction and a stop instruction to the SSR8through TPO. In other words, a pair of a period during which output of a driving instruction continues and a period during which output of a stop instruction continues is one control cycle. Here, if, as indicated by the first control cycle inFIG. 3A, a current value (i.e., a current value measured by the CT9) acquired by the current value acquisition unit33is smaller than the disconnection determination threshold when the SSR control unit32is outputting a driving instruction, the determination unit34determines that the heater7is disconnected, and the warning output unit35outputs a monitoring information warning or a minor fault warning to the controller2, based on this determination. In addition, if a minor fault warning is output to the controller2, the control unit20of the controller2acquires the above warning, and outputs a warning event cancellation instruction to the acquisition unit30of the temperature control unit3if a predetermined condition is satisfied (e.g., if any measures have been taken to address the warning). Upon receiving the cancellation instruction, the acquisition unit30transmits this instruction to the warning output unit35. Upon receiving the event cancellation instruction, the warning output unit35stops outputting the minor fault warning.

Note that, if the current value received from the current value acquisition unit33is continuously smaller than the disconnection determination threshold for a predetermined number of times, the determination unit34may determine that the heater7is disconnected.FIG. 3Bshows “CT current value” and the “warning” graphs (both monitoring information and minor fault warning) in more detail. One dot of the graph “CT current value” represents a timing when the CT9samples a current value. In addition, the solid lines in the “warning” graphs indicate output timings of the monitoring information warning, and the broken lines indicate output timings of the minor fault warning.

As shown inFIG. 3B, if, after determining that the heater7is disconnected, a current value received from the current value acquisition unit33reaches a value larger than or equal to the disconnection determination threshold+a predetermined buffer value (a disconnection determination hysteresis value inFIG. 3B) a predetermined number of times, the determination unit34may determine that the heater7is not disconnected. In this manner, by determining whether or not the heater7is disconnected, based on a predetermined number of current values, the determination unit34can reduce erroneous determinations.

Flow of Warning Output Processing

Lastly, in this embodiment, the flow of processing of the temperature control unit3outputting a warning (warning output processing) will be described with reference toFIG. 4.FIG. 4is a flowchart showing the flow of warning output processing.

When information regarding temperature adjustment is acquired from the controller2, the acquisition unit30of the temperature control unit3transmits the information to the SSR control unit32. The SSR control unit32generates an instruction to drive or stop the heater7according to the information, and transmits the instruction to the SSR8(step S10) and the determination unit34. On the other hand, at the timing when the SSR control unit32transmits the instruction to the SSR8, the current value acquisition unit33acquires a current value from the CT9(step S11). The current value acquisition unit33transmits the acquired current value to the determination unit34.

If an instruction for the SSR control unit32to drive the heater7has been transmitted (YES in step S12), and the current value received from the current value acquisition unit33is smaller than or equal to the disconnection determination threshold (YES in step S13), the determination unit34determines that the heater7is disconnected (step S14). The determination unit34transmits the determination result to the warning output unit35. The warning output unit35generates a warning based on the determination result received from the determination unit34, and outputs the warning (step S15).

On the other hand, if the SSR control unit32has transmitted an instruction to stop the heater7(NO in step S12), or the current value received from the current value acquisition unit33is larger than the disconnection determination threshold (NO in step S13), the determination unit34determines that the heater7is being properly controlled, and then waits until it receives an instruction and a current value from the SSR control unit32and the current value acquisition unit33, respectively.

According to the above-described processing, the temperature control unit3can determine whether or not the heater7is being driven or stopped according to an instruction to the SSR8, based on the content of the instruction to the SSR8, namely, whether it is an instruction to drive the heater7or an instruction to stop the heater7, and the value of the current that flows in the heater7. If the heater7is not properly driven or stopped, it is possible to output a warning to the controller2, which performs output control upstream of the temperature control unit3.

In addition, according to the above-described processing, compared with the case where the SSR8monitors and determines whether or not the heater7is being properly driven or stopped, it is possible to reduce the cost for introducing the SSR8. In addition, it is not required to wire the SSR8and the CT9, and thus it is possible to reduce the man-hours for wiring. Furthermore, it is possible to save the trouble for various settings in the SSR8regarding monitoring of the heater7. Therefore, the temperature control unit3can find an abnormality in the heater7with a simpler configuration, and warn the controller2.

Note that, in this embodiment, if a current value acquired by the current value acquisition unit33is larger than or equal to a predetermined threshold (second threshold) at the timing when the SSR control unit32is outputting an instruction to stop the heater7, to the SSR8, the determination unit34may determine that the heater7is not being properly controlled due to a problem such as break-down of the SSR8. A configuration may also be adopted in which the determination unit34then informs the warning output unit35of the determination result, and the warning output unit35outputs a warning to the controller2.

Furthermore, the warning output unit35may output different warnings (warnings that can be distinguished by the controller2) for a case where the determination unit34determines that “the heater7is disconnected” and a case where the determination unit34determines that “the SSR8is broken down”.

In addition, in this embodiment, the temperature control unit3may be connected to an output apparatus for notifying the user of a warning. The output apparatus may be a speaker, a microphone, or the like. The warning output unit35of the temperature control unit3may also output a warning via the connected output apparatus instead of outputting a warning to the controller2, or in addition to outputting a warning to the controller2.

Accordingly, the temperature control unit3can cause the output apparatus to output a warning generated by the temperature control unit3without an instruction of the controller2. Even if one of the devices upstream of the temperature control unit3, for example, the controller2or the programmable display device1breaks down, and a warning is not successfully transmitted to the upstream device, it is possible to notify the user of the warning.

Second Embodiment

A configuration may also be adopted in which the temperature control unit3according to the invention acquires, from the controller2, an operation amount indicating the ratio of a time during which an output apparatus is driven per unit of time, and performs time proportional output (TPO) of an instruction to drive or stop the heater7to the SSR8such that a constant cycle and the time ratio indicated by the operation amount can be realized. A second embodiment of the invention will be described below with reference toFIG. 5. Note that from this embodiment onward, for convenience of description, the same reference numerals are assigned to members having the same functions as the members described in the first embodiment, and their further description is omitted.

In this embodiment, a control unit20of a controller2outputs an operation amount to a temperature control unit3via a second communication unit23. Specifically, the second communication unit23adds the value of an operation amount to a data block, and returns the data block to the communication network. Here, “operation amount” refers to a value designating the ratio of a time during which the heater7is driven when the SSR8drives the heater7. In the following description, as an example, the control unit20determines, as an operation amount, a value that indicates the ratio of a time during which the heater7is driven, and is expressed as a percentage (%), and outputs the value.

An acquisition unit30of the temperature control unit3acquires the above-described operation amount, and transmits the operation amount to an SSR control unit32. The SSR control unit32performs time proportional output (TPO), to the SSR8, in which a driving instruction and a stop instruction are combined, such that the time ratio indicated by the above-described operation amount can be realized.

FIG. 5is a timing chart showing the change in an operation amount that is acquired by the acquisition unit30(instructed by the control unit20of the controller2) and the change in instruction output of the SSR control unit32. As illustrated, the graph “operation amount” indicates the value (%) of the operation amount acquired by the acquisition unit30. In addition, the graph “TPO output” indicates the content of an instruction (ON or OFF of the heater7) that is transmitted (output) by the SSR control unit32to the SSR8through TPO and the period of TPO. In addition, points a to c indicate timings when the operation amount changes, and arrows A to C indicate timings when changes in operation amount at the corresponding points a to c are reflected.

As illustrated, when an operation amount that is acquired by the acquisition unit30changes, the SSR control unit32reflects the changed operation amount in the current TPO control cycle or the next control cycle.

More specifically, if the operation amount changes at the timing when the SSR control unit32is outputting a stop instruction (point a inFIG. 5), it suffices for the SSR control unit32to perform TPO during a driving time that is based on the changed operation amount, from the next control cycle (arrow A inFIG. 5). In addition, if the operation amount changes at the timing when the SSR control unit32is outputting a driving instruction (point b inFIG. 5), it suffices for the SSR control unit32to adjust the period during which a driving instruction is output, and perform TPO such that the ratio of the driving time of the heater7in the current control cycle matches the time ratio indicated by the changed operation amount (arrow B inFIG. 5).

In addition, if the operation amount changes at the timing when the SSR control unit32is outputting a driving instruction, and, in the control cycle at this time, a driving time larger than or equal to a driving time indicated by the changed operation amount has already elapsed (point c inFIG. 5), it suffices for the SSR control unit32to output an immediate stop instruction, and continue outputting a stop instruction during the remaining time of the control cycle (arrow C inFIG. 5). In this case, the changed operation amount will be accurately reflected from the next control cycle (arrow C′ inFIG. 5).

Thus, even if an operation amount is determined without taking the cycle time of the control unit20and the TPO control cycle into consideration, there is the effect, that the operation amount can be appropriately reflected in TPO by the temperature control unit3acquiring the value of the operation amount from the controller2, and the SSR control unit32performing TPO, as described above.

Third Embodiment

In addition, the temperature control unit3according to the invention may also acquire, from the controller2, first information regarding driving and stopping of the heater7and second information indicating whether or not to autonomously control TPO to the SSR8. In addition, the temperature control unit3may also output an instruction to drive or stop the heater7to the SSR8through TPO in accordance with the first information and second information.

Here, for example, the first information may be the operation amount described in the above embodiments, or may be a control instruction to turn on (drive) the heater7, or to turn off (stop) the heater7. Note that the second information will be described in this embodiment.

The third embodiment of the invention will be described below with reference toFIG. 6. A controller2according to this embodiment is different from the controller2according to the first and second embodiments in that an operation amount (first information) and information (second information) indicating whether an immediate output instruction is ON or OFF are transmitted to a temperature control unit3. Also, the temperature control unit3is different from the temperature control unit3according to the first and second embodiments in that a method for controlling TPO to an SSR8is changed in accordance with the above-described operation amount and whether the above-described immediate output instruction is ON or OFF.

Here, “immediate output instruction” is information that takes two values, namely ON and OFF, and is information indicating whether or not to cause the temperature control unit3to autonomously control TPO to the SSR8. In the following description, if the immediate output instruction is ON, the temperature control unit3does not autonomously control TPO, and if the immediate output instruction is OFF, the temperature control unit3autonomously controls TPO.

Here, “autonomously controlling TPO” refers to the temperature control unit3determining start and end timings of TPO to the SSR8as well as a TPO control cycle based on the internal information of the temperature control unit3itself, for example. If the immediate output instruction is ON, the temperature control unit3cyclically acquires, via data blocks, instructions to start and end TPO or information indicating the start and end timings that have been output from the controller2. The temperature control unit3then changes start and end of TPO and the TPO control cycle in accordance with these instructions or information.

Conversely, “not autonomously controlling TPO” refers to the temperature control unit3determining at least one of start and end timings of TPO to the SSR8and the TPO control cycle based on information (e.g., a control instruction or various parameters) that is acquired from the controller2, for example.

In addition, the control unit20may also have an auto-tuning function for auto-tuning the heater7. “Auto-tuning function” as mentioned in this embodiment refers to a function for calculating various parameters related to output control such as PID control that is executed by the controller2.

Furthermore, a configuration may also be adopted in which, in the case of executing auto-tuning, the controller2stores, in a data block, the value ON as the value of the immediate output instruction, and outputs this block. In addition, a configuration may also be adopted in which, in the case of not executing auto-tuning, the controller2stores, in a data block, the value OFF as the value of the immediate output instruction, and outputs this block. Below, it is assumed that, in the case of executing auto-tuning, the controller2stores, in a data block, the value ON as the value of the immediate output instruction, and in the case of not executing auto-tuning, stores, in a data block, the value OFF as the value of the immediate output instruction.

In addition, if the value of an immediate output instruction read out from a data block is ON, and an operation amount has changed, the temperature control unit3may also update the TPO control cycle from the temperature control unit3to the SSR8.

FIG. 6is a timing chart showing changes in an operation amount and an immediate output instruction (second information) that are output from the control unit20of the controller2, and TPO in an SSR control unit32of the temperature control unit3and its control cycle.

When the immediate output instruction that is output from the controller2is ON (i.e., when the control unit20of the controller2is executing auto-tuning), if an operation amount that is output from the controller2along with the immediate output instruction changes, the SSR control unit32updates the control cycle and starts one new control cycle even if the current TPO has not been performed for a complete period (inFIG. 6, a complete period corresponds to two seconds (s)) of one control cycle (points f, g, h, and i inFIG. 6).

Note that, if a timing when the immediate output instruction changes to ON and a timing when the operation amount changes are the same (point eFIG. 6), the SSR control unit32may update the control cycle as described above, or may reflect the changed operation amount at the timing when the next control cycle begins, without updating the control cycle (an arrow E inFIG. 6).

In addition, if the timing when the immediate output instruction changes to OFF and the timing when the operation amount changes are the same (point j inFIG. 6), the SSR control unit32may also update the control cycle as described above, or may also reflect the changed operation amount at the timing when the next control cycle begins, without updating the control cycle (arrow J inFIG. 6).

As described above, if the operation amount changes while auto-tuning is being executed, the temperature control unit3can ensure that auto-tuning is more accurately performed (more accurately calculate various parameters) on the controller2, by reflecting the change without waiting for the next control cycle.

Particularly when the period of one control cycle is long, and reflection of a change in the operation amount is carried over to the next control cycle, there are cases where there are deviations in the calculation of the above-mentioned parameters. More specifically, for example, in the case of a cooling device such as a fan, instead of the heater7, one control cycle is often long, for example, 20 s. In this case, if a change of the operation amount is reflected in the next control cycle, the controller2will perform auto-tuning that is based on the operation amount before the change, for a period of up to 20 s, and various parameters that are calculated may vary.

By contrast, if the control unit20of the controller2is executing auto-tuning, and the operation amount that is output by the controller2changes, then the temperature control unit3according to this embodiment updates the TPO control cycle, and resumes TPO based on the changed operation amount. In other words, it can be said that the changed operation amount is immediately reflected. Accordingly, the temperature control unit3has the effect that it is able to cause the controller2to more accurately execute auto-tuning.

In addition, when the operation amount changes from 1% or more to 0%, the SSR control unit32of the temperature control unit3may also instruct the SSR8to stop the heater7at the timing when the operation amount changes, regardless of the TPO control cycle. Furthermore, when the operation amount changes from 1% or more to 0%, the SSR control unit32may also instruct the SSR8to stop the heater7at the timing when the operation amount changes, regardless of whether the immediate output instruction is ON or OFF.

Accordingly, when the heater7is to be stopped, the SSR control unit32can transmit, to the SSR8, an instruction to immediately stop the heater7regardless of the cycle of TPO. Therefore, the temperature control unit3can more quickly reflect the operation amount received from the controller2.

In addition, if a plurality of SSRs8are connected to the temperature control unit3, it is desirable that the controller2controls at least one of start and end of TPO between the temperature control unit3and each of the SSRs8and the TPO control cycle, in a distinguished manner (i.e. individually).

In addition, if the temperature control unit3is performing TPO to each of a plurality of SSRs8, and the controller2is to output (or is outputting) the value ON as an immediate output instruction, the controller2may further transmit, to the temperature control unit3, information indicating a start timing of TPO to each of the SSRs8. It is desirable that the acquisition unit30of the temperature control unit3then acquires the above-described information indicating the timing, and starts TPO of each of the SSRs8at the timing indicated by the information indicating the start timing.

More specifically, a configuration may also be adopted in which the controller2adds, in a data block, a value (delay value) indicating the time by which a start timing of TPO to each of the SSRs8is to be delayed from the original start timing of TPO, as the above-described information indicating the start timing, and outputs the data block. A configuration may also be adopted in which the temperature control unit3then reads the delay value, and delays the start timing of each TPO by the time indicated by the delay value.

For example, assume that one temperature control unit3is connected to a plurality of SSRs8, and the SSRs8are each connected to one or more heaters7. In this case, if TPOs to all of the SSRs8are turned ON at the same time, there was a risk that an excessive current flows in the temperature control unit3, causing a malfunction.

By contrast, in the controller2and the temperature control unit3according to this embodiment, for example, by the controller2instructing different start timings of TPO between the temperature control unit3and the respective SSRs8(e.g., different delay values of TPO to the SSRs8), it is possible to prevent an excessive electric current from flowing as described above.

Modified Example

In the above embodiments, a system for adjusting the temperature of a certain target object by controlling driving of the heater7has been described. However, the output control system100according to the invention can be applied to not only temperature adjustment but also various types of output control.

For example, a configuration may also be adopted in which the output control system100according to the invention has a burner in place of the heater7, and performs temperature adjustment of a target object (e.g., water or metal) by controlling driving (ON) and stopping (OFF) of the burner. In this case, the SSR8(and the CT9) may also be a control motor that has a function similar to that of the SSR8(and the CT9).

In addition, a configuration may also be adopted in which the output control system100according to the invention has a tank filled with a coolant (e.g., water) in place of the heater7, and performs temperature adjustment of a target object by adjusting the area of the coolant that comes into contact with the target object, or adjusting the flow rate of the coolant. In this case, the SSR8(and the CT9) may also be a valve mechanism for adjusting the area of the coolant that comes into contact with the target object, the flow rate, and the like, the valve mechanism including a control function similar to that of the SSR8(and the CT9).

In addition, a configuration may also be adopted in which the output control system100according to the invention has a fan in place of the heater7, and performs temperature adjustment of a target object by controlling driving and stopping of the fan. In this case, the SSR8(and the CT9) may also be a mechanism that has a control function similar to that of the SSR8(and the CT9), and controls driving, stopping, the rotation frequency, and the like of the fan.

In addition, a configuration may also be adopted in which the output control system100according to the invention has a Peltier element in place of the heater7, and performs temperature adjustment of a target object by controlling the Peltier element. In this case, the SSR8(and the CT9) may also be a Peltier controller that has a control function similar to that of the SSR8(and the CT9).

Realization Example Using Software

The controller2and control blocks of the temperature control unit3(in particular, the control unit20, the acquisition unit30, the SSR control unit32, the current value acquisition unit33, the determination unit34, and the warning output unit35) may also be realized by logic circuits (hardware) formed on an integrated circuit (IC chip), or may also be realized by software using a CPU (central processing unit).

In the case of the latter, the controller2and the temperature control unit3have a CPU that executes an instruction of a program that is software for realizing each function, a ROM (read only memory) or a storage apparatus (these are referred to as “recording media”) that stores the program and various types of data in a computer-readable (or CPU-readable) manner, a RAM (random access memory) to which the program is loaded, and the like. An advantage of some aspects of the invention is then achieved by a computer (or a CPU) reading the above-described program from the above-described recording medium, and executing the program. A “non-transitory tangible medium” such as a tape, a disk, a card, a semiconductor memory, and a programmable logic circuit can be used as the above-described recording medium. In addition, the above-described program may also be supplied to the above-described computer via any transmission medium (e.g., a communication network or broadcast wave) that can transmit the program. Note that the invention can also be realized in form of data signals that are obtained by embodying the above-described program through electric transmission, and are embedded in carrier waves.

An output control unit according to one aspect of the invention includes an acquisition unit that acquires, from a control apparatus, an operation amount for a switching apparatus that switches between driving and stopping of an output apparatus and an instruction output unit that performs time proportional output to the switching apparatus based on the operation amount acquired by the acquisition unit.

A control method of an output control unit according to one aspect of the invention includes an acquisition step of acquiring, from a control apparatus, an operation amount for a switching apparatus that switches between driving and stopping of an output apparatus and an instruction output step of performing time proportional output to the switching apparatus based on the operation amount acquired in the acquisition step.

According to the above-described configuration and processing, the output control unit itself that has acquired the operation amount from the control apparatus performs time proportional output to switching apparatus. Here, “operation amount” refers to the ratio of a time during which the output apparatus is driven. Therefore, for example, compared with a case where an instruction of time proportional output generated by the control apparatus is acquired, and is transmitted to the switching apparatus, the output control unit can perform time proportional output independently of the cycle time of the control apparatus.

Therefore, it is possible to avoid deviation of time proportional output due to the cycle time of the control apparatus. In addition, it is also possible to determine an operation amount without taking the cycle time of the control apparatus into consideration, and perform time proportional output.

In addition, in the output control unit, the acquisition unit may also periodically acquire the operation amount from the control apparatus. Accordingly, it is possible to perform time proportional output without being affected by the acquisition cycle of the operation amount, and thus more accurate output control is possible.

In addition, in the output control unit, the acquisition unit may also be connected to the control apparatus via a field network. In the case of performing communication using a field network, there are cases where communication is cyclically performed. However, according to this configuration, it is possible to perform time proportional output without being affected by the communication cycle, and thus more accurate output control is possible.

In addition, in the output control unit, the instruction output unit may perform time proportional output of an instruction, to the switching apparatus, that instructs the switching apparatus to drive or stop the output apparatus, and if the operation amount that is acquired by the acquisition unit changes during one cycle of the time proportional output and at a timing when an instruction to stop the output apparatus is being output to the switching apparatus, the instruction output unit may perform the time proportional output based on the changed operation amount, starting with the next cycle following the one cycle. Accordingly, it is possible to reflect the change of the operation amount at a constant cycle without changing the period of one cycle of time proportional output.

In addition, in the output control unit, the instruction output unit may perform time proportional output of an instruction, to the switching apparatus, that instructs the switching apparatus to drive or stop the output apparatus, and if the operation amount that is acquired by the acquisition unit changes during one cycle of the time proportional output and at a timing when an instruction to drive the output apparatus is being output to the switching apparatus, the instruction output unit may perform the time proportional output based on the changed operation amount, during the one cycle. Accordingly, it is possible to reflect the change of the operation amount at a constant cycle without changing the period of one cycle of time proportional output.

In addition, in the output control unit, if the operation amount that is acquired by the acquisition unit changes at said timing, and the switching apparatus has driven the output apparatus for at least a period indicated by the changed operation amount in the one cycle, the instruction output unit may continue outputting an instruction to stop the output apparatus to the switching apparatus for the remaining time of the one cycle. Accordingly, it is possible to reflect the change of the operation amount at a constant cycle without changing the period of one cycle of time proportional output.

An output control system according to one aspect of the invention includes the output control unit and the control apparatus. Accordingly, it is possible to realize an output control system that can prevent deviation of time proportional output due to the cycle time of the control apparatus.

The invention is not limited to the above embodiments, and various modifications can be made within the scope of claims, and an embodiment acquired by appropriately combining technical means disclosed in different embodiments is also included in the technical scope of the invention.

LIST OF REFERENCE NUMERALS