2
INTRODUCTION
2.1
Preface
The aim of this Design Guideline is to provide you with practical information on how to plan your automation plant using Bürkert devices based on the Bürkert system bus (büS). The various aspects involved in the planning, assembly and operation processes are all considered. The structure of the Design Guideline helps you build knowledge and apply it through different steps based on examples.
2.2
What is the Bürkert system bus (büS/EDIP)?
The Bürkert system bus, also referred to as büS, is based on the widely spread CANopen standard and is fully downwards compatible to this standard. The büS concept does not require a master. Field devices can easily interchange process data and detailed diagnostic data. A gateway allows access to this information from a higher-level system. The Bürkert digital device platform EDIP (Efficient Device Integration Platform) opens the door to endless possibilities for a digital future.
2.3
For whom is this Design Guideline intended?
The Design Guideline is intended for engineers or plant builders who are familiar with the planning and en- gineering of automation plants containing fieldbuses, especially CAN-based protocols like CANopen and DeviceNet. The Design Guideline summarises the additional knowledge required to plan büS/EDIP net- works. The most important steps for planning, creating and commissioning büS devices are outlined herein.
2.4
What is the purpose of the Design Guideline?
The Design Guideline aids the planning of a büS/EDIP system. In a comprehensive approach based on illus- trative and practical examples, the Design Guideline walks you through the Do’s & Don’ts to ensure a fully functional system. This Design Guideline explains in detailed individual steps how to plan a büS network.
2.5
Bürkert quality standard
All devices with a büS/EDIP interface have to obtain an internal certification which consists of a software and hardware measurement. Therefore, we can ensure that all Bürkert devices have attained the same quality standard. Currently, there are two approved CAN transceivers that meet these requirements. Type büS Creating a rough project plan
3

Block diagram, devices, postion, protocols 3.1 Which devices are planned? Create an overview of the positioning of your devices. Are the devices distributed in an equidistant or a non-equidistant manner? Fig. 1: Project plan 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02. Getting to know the basics of a büS infrastructure – accessories, cables, 4

4.1
What is the purpose of the various accessories In this chapter, the various components required for cabling are explained in detail. büS devices are widely equipped with standard M12 connectors and. different accessories are available for a range of cabling tasks.
4.2
Accessories
4.2.1
Y-connector
Definition: A Y-connector has three M12 connectors in total. On one side of the connector, there is one male and one female connector. On the other side, there is one female connector. Purpose: Since most büS devices have a single M12 büS connector, the Y-connector enables another con- nection option to the next device. The single connector side is connected to the device and the other two connectors may be used for the devices to the left and the right. Fig. 2: Y-connector A Y-connector with interrupt is also available. This connector is used for segmenting power. The pin 2 con- nection is interrupted. It is therefore possible to use a new power supply for the next büS segment if the limit of 100 W has been reached. Fig. 3: Y-Connector with interrupt Type büS Getting to know the basics of a büS infrastructure – accessories, cables, pin assignment
4.2.2
Passive junction box
Definition: A passive junction box is an IP65/IP67 block with connectors for the power supply and multiple büS connectors. It is a passive module and, therefore, does not have to be configured. Purpose: The passive junction box allows multiple connections to büS devices in a star form. The Y-con- nectors on each device become redundant when using a passive junction box, thus making cabling in the field much simpler.
4.2.3
Gender changer
Definition: A gender changer is an IP65/67 component with two male M12 connectors. Purpose: It is used to connect two female M12 connectors. Fig. 5: Gender changer 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.0 Getting to know the basics of a büS infrastructure – accessories, cables, pin assignment
4.2.4
Termination
Definition: A termination resistor is available as an M12 connector (female and male) or as a chip and has to be used twice in one network. Purpose: To avoid signal reflections in the cable, the büS network always needs to be terminated with two 120 Ω resistors at the ends of the cable. One is required at the beginning of the network and one at the end. Fig. 6: Termination Fig. 7: Termination resistor chip
4.3
Cable configuration
There are two types of cable: connecting cables and extension cables. All cables are available with different cable lengths. An overview can be found in the appendix.
4.3.1
Characteristic impedance and cables standards
All nodes are connected to each other through a physically conventional two-wire bus. The wires are a twis- ted pair with a 120 Ω (nominal) characteristic impedance. CiA 301 (CANopen application layer) is standard- ised as EN 50325-4.
4.3.2
Connecting cables
Definition: Connecting cables are equipped with a female M12 connector on one side and with open leads on the other. Purpose: These cables connect a device with a terminal block to an M12 connector, e.g. gateway Type ME43.
4.3.3
Extension cables
Definition: Extension cables are equipped with a female M12 connector on one side and with a male M12 connector on the other. Purpose: These cables are used to connect a device with an M12 connector. Type büS Getting to know the basics of a büS infrastructure – accessories, cables, pin assignment
4.4
Pin assignment
Various standard connectors are available for Bürkert devices with a büS interface.
M12 connector male, 5-pin (A-coded)

Tab. 1: M12 connector male, 5-pin (A-coded)
4.4.2
M12 connector male, 8-pin (A-coded)
M12 connector male, 8-pin (A-coded)

4.4.3
Terminal block, 5-pin

Tab. 3: Terminal block, 5-pin Type büS Getting to know the basics of a büS infrastructure – accessories, cables, pin assignment
Tab. 4: Terminal block, 4-pin
5

5.1
What is a bus topology and why do you need it?
The arrangement of different devices on the bus defines the topology. Different topologies influence the quality of communication and certain topologies are, therefore, recommended to achieve a good network design.
5.2
Common terms of bus topology
5.2.1
Trunk line
A trunk line is the main part of a CANopen cabling solution. All devices and junction boxes are connected to it.
5.2.2
Stub line
A stub line is a branch of the trunk line and allows connection to a device that is not located close to the trunk line. The use of stub lines must be avoided as much as possible. However, there are several limita- tions depending on the baud rate of the network.
5.2.3
Overview of cable lengths
Overview of maximum cable lengths in the CANopen specification:
This table shows an overview of theoretical values for an ideal network. Nevertheless, there are more de- pendencies regarding the trunk line length, the stub line length, the amount of process data and the baud rate. Fig. 8: Example
5.3

The following topologies achieve the best results with regard to signal quality. 5.3.1 Line topology (daisy chain) All devices are connected in single row without a stub line. Fig. 9: Line topology
5.3.2
Line topology with stub lines
The trunk line of the network is connected directly to the next device. If this is not possible, use a stub line. Avoid stub lines as much as possible and keep them short. Please note the maximum stub line length that depends on the baud rate. 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02 Fig. 10: Line topology with stub lines Getting to know the büS topologies
5.3.3
Star topology
A star topology is used to interconnect devices when space is limited and a setup with a daisy chain topo- logy is not possible. Fig. 11: Star topology
5.4
Which topologies are NOT recommended?
The topologies in this chapter are possible, but various criteria have to be observed to ensure the network works properly.
5.4.1
Tree topology
For signal quality, it is not recommended to use a tree topology. Cascading of the passive junction boxes is restricted to three. If more devices are needed, it is necessary to interconnect the trunk lines of the passive junction boxes and to not cascade more than three devices. Otherwise, the maximum stub line length is ex- ceeded and errors may occur. 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.000 Fig. 12: Tree topology Which topologies are NOT permitted 5.5 The topologies described in this section are not permitted. Never use them in a büS or CANopen network.
5.5.1
Ring topology
A ring topology is not permitted in a CANopen network. Choose another topology for the network. AN 1000462349 ML Version: J Status: RL (released | freigegeben) printed: 19.02. Detailed project plan 1
6

6.1
Floor plan
Create a detailed project plan using the aforesaid information about devices, cables lengths, topology, junc- tion boxes and Y-connectors. Are the devices close to each other? YES: plan the network with a passive junction box NO: plan the network with Y-connectors Rules: • Connect all the accessories on the trunk line • Connect the accessories directly to the device –  Use stub lines to connect the devices –  Avoid long stub line lengths
6.1.1
Network with a junction box
In a network with one passive junction box, all the cables will be viewed as stub lines since there is no trunk line. Keep the stub lines as short as possible. Fig. 14: Network with a junction box
6.1.2
Network with Y-connectors
A network with Y-connectors without stub lines (directly connected to the M12 connector of the device) Fig. 15: Network with Y-connectors without stub lines Detailed project plan 1 Network with Y-connectors and stub lines Fig. 16: Network with Y-connectors and stub lines
6.1.3
Mixed network
In a mixed network, it is important to indicate the total length of the cables. This includes the length of all trunk lines and stub lines. Fig. 17: Mixed network
7

7.1
Termination resistors
Termination resistors are located on each side of the trunk line. The impedance is approximately 60 Ω between CAN-HIGH and CAN-LOW. Exception: In a large network with long stub lines, the longest distance between two devices should be es- timated. It is also recommended to choose the longest distance in a network that consists of more than one passive junction box. Fig. 18: Termination resistors
7.2
Connection for diagnostics
We recommend providing a free connection for diagnostics. A port of the junction box or an extra Y-con- nector in the network can be used. This access is important for fast diagnostics with büS stick and the Bürkert Communicator software. Furthermore, it can be used for measurements with external tools, e.g. GEMAC CANBUS Tester 2. In this case, a measurement connection at both ends is recommended.
8

8.1
Completion – floor plan
A cabling plan using the accessories, cables lengths, topology, junction box, Y-connector, termination res- istor and a diagnostics port must be created. 8.1.1 Fig. 19: Network with a junction box In a network with a passive junction box, the termination resistors are connected to the devices with the longest distance to each other. 8.1.2 Network with Y-connectors Fig. 20: Network with Y-connectors Network without stub lines. The Y-connector is connected directly to the device. Detailed project plan 2
8.1.3
Mixed network
Fig. 21: Mixed network For good signal quality, it is important to determine the longest distance between two devices in the entire network. Place the termination resistors close to these devices. This helps to reduce the signal reflections. Please do not exceed the maximum stub line length. 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02.2
9

9.1
Power segments
Calculate the overall power consumption of all the devices in the network. Build power segments with a maximum load of 100 W. This refers to the M12 connector (A-coded). This component has a current limit of approx. 4 A.
9.1.1
One power segment
In a network with one power supply, overall power consumption is limited to 100 W. Termination resistor Power supply Fig. 22: One power segment
9.1.2
Additional power supply
For higher power consumption, use additional power supplies and Y-connectors with interrupt to utilise power from a second power supply. Fig. 23: Additional power supply
9.2
Rule of thumb
The rule of thumb is that 1 W load per metre results in a voltage drop of 1 mV. A maximum voltage drop of 5 V is allowed. Some devices will shut down if the supply voltage is lower than 19 V. Therefore, refer to the respective data sheet for more information. 000462349 ML Version: J Status: RL (released | freigegeben) printed: 19. Detailed project plan 3

10.1
Cabling plan
Rough cabling plan, topology, rules of cabling (table). Place your power supply (power < 100W) close to the load. Y-connector, passive junction box, external power supply, galvanically isolated switched-mode power sup- plies (recognised UL Class 2). Fig. 24: Network with junction box 10.1.2 Network with Y-connectors Fig. 25: Network with Y-connectors 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.0 Detailed project plan 3 Fig. 26: Mixed network AN 1000462349 ML Version: J Status: RL (released | freigegeben) printed: 19.02.20

11.1
Shielding of EDIP devices
Detailed shielding information for each device can be found in pin assignment of technical data sheet and operating instructions. There are three types of device-internal shieldings:
000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02
11.3
Network with direct shielded devices
Shield is grounded at multiple points to FE. Direct shield connection on both cable ends or at multiple devices to FE has shielding effects against E and H fields. But take care for equipotential FE grounding area to prevent compensation currents over shield! Fig. 27: Direct shielded device If equipotential FE area is not feasible, e.g. between two buildings, there are some measures to improve; e.g. add bypass conductor or a grounded cable duct nearby büS cable. Fig. 28: Direct shielded device, 2 buildings Explanation of graphic elements: • Each device-internal shielding (None, Direct, RC) is said in brackets. • Green line represents büS cable shield. büS network shielding
11.4
Network with RC shielded devices
In a network with RC shielded devices, shield must be only on one point directly connected to FE. This shielding set-up only shields E-Fields, but it is usually preferred, when FE area connection is poor. • Either by using one direct shielded device. Fig. 29: RC shielded • Or by grounding the cable shield directly anywhere in network, e.g. in the middle or near a source of EMC disturbance for immediate derivation. In general, a distance between H-Field emitting machines and büS network is recommended. If not pos- sible, use grounded metal duct for additional shielding the büS cable in whole. Fig. 30: RC shielded 000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02.
11.5
Network with none shield connected devices
Not recommended to have “None” shield connected devices only. Network shield would be floating at all and this is equal to unshielded. When using devices without an internally connected shield, take care that one end of büS shield must be connected directly to FE. Either a direct or RC shield connection can be used at the other shield end. The devices of the shielding type "None" are located in between with minimal stitches (e.g. with T-piece). • For this, use either devices at the ends of network. Fig. 31: büS network with devices without internal shield connection (shielding "None") • Or connect cable shield directly to FE on both ends (example).
11.6

A planned büS network (a) is revised, some issues were identified (b) and finally some solutions are found (c). a) Initial network Fig. 33: Initial network b) Problem identification FE with potential differences between building A and B FE with potential differences between building A and outside Long büS line with open shield to device 7 with no shield connection. Fig. 34: Problem identification 000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02. büS network shielding c) Modifications (possible solutions) Applied solutions: Add both-end FE grounded and low-impedance metal duct or bypass conductor between building A and B Add both-end FE grounded and low-impedance metal duct or bypass conductor, led as near as possible to device 4. Reduce unshielded cable length, by changing trunk line: Shield is led directly past device 7 (e.g. with T-piece) and grounded at device 6 afterwards. Fig. 35: Examples of possible modifications AN 1000462349 ML Version: J Status: RL (released | freigegeben) printed: 19.02.
12

12.1
Termination resistor
Termination resistors are located on each side of the trunk line. Each resistor has a resistance of approx. 120 Ω. Therefore, a network with a termination resistor at both ends has an impedance of 60 Ω. Resistors are available as a male or female M12 connector. Additionally, a chip resistor for ME43 and valve island Type 8652 is available.
12.2
Signal reflections
There might be more than one reason for signal reflections in a network. This depends on the number of devices, the baud rate, the amount of process data, the position of the termination resistors and the posi- tion of the measurement port. Massive signal reflections occur if the position of the termination resistors is not selected correctly.
12.3
Passive junction box
Passive junction boxes are used for the distribution of devices that are close to each other. In a network with a passive junction box, it is important to determine the longest distance between two devices and to place the termination resistor there. In this case, it is not recommended to place these resistors on the trunk line.
12.4
Diagnostic port
In a büS network, one diagnostic port should be placed in one plant. It is used for fast access with the Bürkert Communicator or also a third-party tool, e.g. GEMAC CAN Bus Tester 2.
12.5
Baud rate
The default baud rate of all Bürkert devices is 500 kbit/s. In the case of a poor measurement result, it is possible to reduce the baud rate to 250 kbit/s or 125 kbit/s. Therefore, longer cables can be used in the network. Please note that the total time of a firmware update increases when the baud rate is reduced to a lower communication speed.
12.6
büS stick
The büS stick is a USB-to-CAN converter and is connected to a laptop/PC with the Bürkert Communicator. It is used for the diagnostics, start-up and parameterisation of devices.
12.7
Stub lines
The total length of stub lines in the entire network should be reduced as much as possible. It is impossible to calculate exactly the impact that a one metre stub line has on reducing the signal quality in percentage terms.
12.8
Bus load
The maximum bus load is 40%. The specific bus load of a device is specified in the communication data sheet. To calculate the total bus load, sum up the values from the communication data sheet for all devices.
12.9
Power consumption
It is important to consider the power consumption of a device as early as possible in the planning. Using the information about the total power consumption of the network, the accessories and the number of power supplies can be planned. Furthermore, the permitted voltage ripple of a device must be considered. For devices with direct access, e.g. MFCs, it is important to have a low residual ripple. For sensors, the impact is not that significant.
12.10
Grounding power supplies
Power supplies should not be earthed, but it is important to ensure galvanic isolation. Otherwise, huge loops may develop that can have a negative impact on the entire network.
12.11
Shielding of büS network
Provide good, continuous functional earth (FE) with low impedance and noise. If this cannot be ensured in the area of the büS network, use a low-impedance metallic cable duct or bypass conductor grounded on both sides to prevent compensation currents over büS shield. Connect devices of the internal shielding "None" directly to the büS strand (without stitch). The shielding must be on upstream or downstream devices in the network, but at least on end devices. Connect at least one point of büS shield directly to FE (e.g. by using a device with direct FE connection to shield). Keep a distance from H-Field emitting machines with high power consumption. If not possible, use metal duct grounded on both sides or multiple times for additional shielding of the büS cable . büS networks with maximum network expansion
13
büS NETWORKS WITH MAXIMUM NETWORK
EXPANSION
Networks with varying devices, cable lengths, baud rates and topologies are tested. The networks shown here should only serve as examples of what is possible and are intended as a refer- ence point for your own setup. For large networks close to the limit or even above, it always makes sense to check the network quality.
13.1
Line topology
For the baud rates 500 kbit/s, 250 kbit/s and 125 kbit/s the maximum cable length and the maximum num- ber of devices have been determined.
13.1.1
500 kbit/s
Communication of the entire büS network worked with up to 84 devices and 1 büS stick. The total cable length was 75 metres. Termination resistor Power supply |Measurement point Diagnostics Fig. 36: 500 kbit/s, 84 devices, cable length 75 m Measurements with a maximum cable length of 100 metres was possible with 44 devices and 1 büS stick. A length of 100 metres is defined as the limit in the CANopen specification. IR Termination resistor PS Power supply Measurement Diagnostics Fig. 37: 500 kbit/s, 44 devices, cable length 100 m point büS networks with maximum network expansion
13.1.2
250 kbit/s
The network was tested with 84 devices and a total cable length of 175 metres and worked without any er- rors. Fig. 38: 250 kbit/s, 84 devices, cable length 175 m The system setup consists of 41 büS devices and 1 büS stick with a total cable length of 250 metres, which is defined as the maximum. 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02. Type büS büS networks with maximum network expansion
13.1.3
125 kbit/s
The network can have a total cable length of 475 metres with 84 devices and 1 büS stick. Fig. 40: 125 kbit/s, 84 devices, cable length 475 m With 125 kbit/, it is possible to connect up to 53 devices with a total cable length of 500 metres. Fig. 41: 125 kbit/s, 53 devices, cable length 500 m 1000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02.1 büS networks with maximum network expansion
13.2
Star topology with a junction box
If a passive junction box is used, all the cables are stub lines. With a baud rate of 500 kbit/s, a total stub line length of 25 metres is permitted. The maximum length of each stub line is limited to 5 metres. If all the stub lines have the same length, the position of the termination resistor is irrelevant. Fig. 42: Star topology with a junction box
13.3
Tree topology with a junction box
With a tree topology, a total cable length of 94 metres was measured with 23 devices in the network. The stub line length varies between 1 and 10 metres. Fig. 43: Tree topology with a junction box 000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.02
14

14.1
Sporadic disconnections
Description:
In a faulty network, it is possible to experience sporadic disconnections. Therefore, one or more devices may disappear for a few seconds. This is an indication that something has gone wrong.
Common problems:
• More or less than two termination resistors • Total cable length is too long • Total stub line length is too long •  Bus load is too high • Undersized power supply
Solution:
• Measurement of the impedance between CAN-High and CAN-Low. The impedance should be approx. 60 Ω • Reduce the cable length • Reduce the baud rate to the next lower communication speed • Create power segments in the network with more power supplies and Y-connectors
14.2
Red LED (failure)
Description: The LED of a single device or the entire EDIP network lights up red. Common problems: • Incorrect connection to the PLC •  Device reached critical limit, e.g. power supply too low • EDIP partner is missing
Solution:
• Check the cabling to the PLC and configure the PLC with the description files of the device • Check the messages of the device with the PLC or Bürkert Communicator • Check the partner name and mapping
14.3
Orange LED on the device (functional check)
Description: The LED of a single device or the entire EDIP network lights up orange. Common problems: •  Partner allocation is active • PLC has “stopped” • Simulation is active • Manual mode
Solution:
• Wait until the device finds its partner in the network • Set the PLC to “RUN” • Deactivate simulation • Set the device to “Automatic”
14.4
Yellow LED on the device (out of specification)
Description: The LED of a single device or multiple devices in the network lights up yellow. Common problems: • Device has reached an internal limit, e.g. temperature • Teach function is required •  Device cannot reach the setpoint
Solution:
• Check the limits and messages with the PLC or Bürkert Communicator • Start the device teach function • Check the medium pressure
14.5
Blue LED on the device (maintenance required)
Description: The LED of a single device or multiple devices in the network lights up blue. Common problems: • Switching cycle counter limit has been reached • Config-Provider/Client missing •  Damaged calibration curve
Solution:
• Reset the switching cycle counter • Replace the missing device • Recalibrate the device Type büS Troubleshooting
14.6
Restarting some devices
If the LED first lights up yellow and then turns red or green, it is an indication that the power supply has reached a limit for stable operation. If one device switches an actor on, the voltage drop is so high that the power falls below the limit and a restart will be performed.
15
APPENDIX
15.1
Accessories - büS stick interface sets

Type büS Appendix
15.4
Accessories - extension cables

15.5
Accessories - power supplies

15.6
Accessories - power cables

Further accessories available on the Bürkert homepage. 000462349  ML  Version: J Status: RL (released | freigegeben)  printed: 19.0