Remote maintenance system

A system is shown for interfacing between a work station or intelligent terminal device and a number of maintainable telecommunication systems. This system provides for interfacing between an intelligent CRT terminal and up to 26 remotely located maintenance processor units. This system provides the CRT attendant or crafts person with the ability to trouble-shoot or perform diagnostic testing upon a maintenance processor unit which is remotely located. In addition, the work station or intelligent terminal may be remotely located from the interface circuitry. This system establishes a connection between the work station or intelligent terminal and a particular maintenance processor unit. Once that connection is established, the maintenance processor unit of that telecommunications system reports diagnostic and trouble-shooting type information. This system also provides for manual reset and self test capabilities. This system provides for a variable BAUD rate which may be preprogrammed into a microcontroller device.

BACKGROUND OF THE INVENTION 
The present invention pertains to maintenance of telecommunication 
switching and transmission systems and more particularly to remote 
monitoring and access of a number of maintainable electronic switching and 
transmission systems from a centralized intelligent terminal or work 
station. 
Typically, switching and transmission systems require a crafts person to be 
physically present at the site of the equipment to perform maintenance 
tests and status checks. Having a crafts person travel to each of the 
sites of the equipment is expensive. For situations in which large amounts 
of equipment exist, several crafts people may be required in order to 
effectively monitor all the equipment. This type of arrangement entails 
much travel by the crafts person, along with transporting the required 
interface and test equipment. 
With the advent of work stations and intelligent terminal devices, 
communications between these work stations or intelligent terminals and 
other work stations, intelligent terminals or devices is greatly 
facilitated via telephone lines. Therefore, it is advantageous for a 
single source to monitor a number of maintainable switching and 
transmission systems. 
Accordingly, it is an object of the present invention to provide an 
interface between a single work station or an intelligent terminal and a 
number of maintainable telecommunication systems. 
SUMMARY OF THE INVENTION 
A terminal switching unit for a plurality of maintenance system has a 
intelligent terminal, a number of maintenance processor units residing in 
transmission and switching systems and a switching arrangement connected 
between the intelligent terminal and the maintenance processor units. The 
intelligent terminal transmits commands and receives data for display. 
Each switching and transmission system includes one corresponding 
maintenance processor unit. Each maintenance processor unit operates to 
gather and to transmit data and also to perform diagnostic testing. 
The switching arrangement analyzes a command from the intelligent terminal 
and determines which particular maintenance processor unit has been 
selected. This maintenance processor unit is then connected to the 
switching arrangement. The switching arrangement facilitates the transfer 
of data from the maintenance processor unit selected to the intelligent 
terminal for display. 
In addition, the switching arrangement also transmits a command to the 
maintenance processor unit to perform diagnostic testing. After the 
maintenance processor unit has performed the diagnostic testing, it 
transmits the resultant data to the switching arrangement for subsequent 
display on the intelligent terminal.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 depicts a terminal switching unit for a plurality of maintenance 
system. A local CRT (intelligent terminal or work station) is shown 
connected to the CRT switching unit (CSU). The remote CRT is shown 
connected through modem 40 and through modem 30 to the CSU. The remote CRT 
is also an intelligent terminal or work station. 
The CSU is connected to up to 26 maintenance processor units (MPUs). The 
MPUs are systems which reside in either switching or transmission systems. 
The MPUs provide for maintenance and diagnostic interface with each of the 
associated switching and transmission systems. The CSU may connect the 
local CRT or the remote CRT to any of the 26 MPUs. An attendant or crafts 
person at the local or remote CRT may, via input commands, trouble-shoot 
or perform diagnostic testing on any of the switching or transmission 
systems, having an MPU. The CSU allows :, the attendant at the CRT to 
obtain status information of any : particular switching or transmission 
system. 
Once the CSU establishes a connection between a CRT and the MPU of a given 
switching or transmission system, the MPU of that system oversees the 
reporting of maintenance and diagnostic data to the CSU. The CSU then 
facilitates transfer of the data between the MPU and either of the CRTs. 
The CSU allows selection of any of the 26 MPUs by either the local CRT or 
the remote CSU. The CRT interfaces between a selected MPU and the remote 
CRT via modems 30 and 40. All the inputs and outputs to and from the CSU, 
except power and electrical ground, are EIA standard RS-232-C serial 
interface signals. The CSU provides a variable BAUD rate for interfacing 
to special I/0 devices. The BAUD rates are preprogrammed into the CSU 
software and may be rates of 300 BAUD or more. In addition, the CSU 
includes hardware for self test and resetting functions. 
FIG. 2 is a block diagram of the CSU switching unit. The heart of the 
switching unit is the microcontroller 200. The microcontroller 200 may be 
implemented with an Intel device part no. 8031. Intel is a register 
trademark of the Intel Corporation. 
The CSU circuitry is implemented on one physical printed wiring card. This 
card may be plugged into standard switching and transmission system card 
files. This printed wiring card has a face plate, shown in FIG. 3. Various 
connections, switches and indicator lamps are incorporated on the face 
plate. 
Input and output from the local CRT; and is transmitted to UART 230. Input 
and output from the remote CRT is via modem 30 and 40 and the remote lead 
of UART 230. UART 230 is a universal asynchronous receiver/transmitter. 
These input commands are transmitted via the data bus (D0-D7) to 
microcontroller 200. UART 230 may be implemented with an Intel device part 
no. 8274, multi-protocol serial control device. Microcontroller 200 is 
connected via a bidirectional link 218 to relays 220. Relays 220 select a 
connection to one of the 26 MPUs. 
Microcontroller 200 is connected to latches 205. Latches 205 operate to 
latch an output memory address. The bidirectional data bus D0-D7 connects 
both RAM 210 and EPROM 212 to microcontroller 200. Microcontroller 200 is 
connected to RAM 210 via the address bus leads A0 through A11. 
Microcontroller 200 is also connected to EPROM 212 via address bus leads 
A0 through A13. RAM 210 is a random access memory device providing a 2K by 
8-bit memory. EPROM 212 is an electronically programmable read only memory 
of size 8K by 8-bits. 
Timer 245 is connected to UART 230, microcontroller 200 and to clock 240. 
Timer 245 may be implemented with an Intel programmable interval timer 
part no. 8254. 
The clock 240 drives all the timing functions of CSU. The clock is 
connected to microcontroller 200, to timer 245, to UART 230 and to watch 
dog timer 242. The clock provides a frequency of approximately 11.059 
megahertz. 
DC to DC converter 270 provides all power to this circuit as well as for 
illuminating the lamp indicators on the face plate via a connection to the 
LEDs 250. The DC to DC converter 270 will take either -48 volts or -24 
volts as an input , and provide +12 volts, -12 volts and +5 volts as 
outputs. 
The LEDs 250 and the switches 260 are connected to the microcontroller 200. 
The microcontroller 200 serves to light or extinguish each of the light 
emitting diodes (lamps) 250. Switches 260 serve to input various functions 
to microcontroller 200. These function included self test and general 
reset functions. 
The local CRT is connected to UART 230 via the local CRT lead. The remote 
CRT via modem 30 is connected to modem 40 with modem 40 connected to UART 
230 via the remote CRT lead. Each of the MPUs is connected to relays 220 
via a corresponding lead MPU1 through MPU26. 
Commands are input from the local or remote CRTs to UART 230. These 
commands are transferred from UART 230 via the data bus D0-D7 to 
microcontroller 200. Then, microcontroller 200 analyzes the command. 
Microcontroller 200 determines which MPU is requested by the command and 
connects to that MPU via relays 220. When the particular MPU responds, the 
response is transmitted through relays 220 via the bidirectional link 218 
to microcontroller 200. 
EPROM 212 contains the operating firmware for microcontroller 200. RAM 
memory 210 is a scratch pad data area for receiving and holding data 
transmitted by an MPU to the CSU. When RAM memory 210 has been filled with 
MPU data, microcontroller 200 will transmit a message to the MPU, causing 
the MPU to cease transmitting any more data, until RAM memory 210 has 
available storage. 
Microcontroller 200 displays the data transmitted received from an MPU upon 
the CRT which had made the request. Then, the MPU will control sending all 
requested data, until this data has been sent to the CSU and displayed 
upon the appropriate CRT. 
Timer 245 is a microcomputer peripheral device which supports asynchronous, 
byte synchronous and bit synchronous : protocols. Asynchronous 
communication protocols are used by the CSU during its interface with the 
CRTs. Timer 245 supports two receiver/transmitter channels. One channel 
supports the local CRT and the other channel supports the remote CRT. 
Clock 240 drives the other various timing functions of the CSU. These 
functions include the microcontroller, timer 245, UART 230, and watch dog 
timer 242. The watch dog timer circuitry 242 is located on the CSU printed 
wiring card and provides a circuit which must be reset by the 
microcontroller 200 software every 42 milliseconds. Failure of the 
microcontroller 200 software to reset the watch dog timer circuitry will 
result in a watch dog time-out. As a result of the watch dog time-out, 
watch dog circuit 242 will issue a reset signal to microcontroller 200 and 
to associated latching circuitry. This condition will also cause the local 
alarm lamp LED (Light Emitting Diode) to be turned-on. This local alarm 
lamp, along with other lamps, switches and a connector, are located on the 
face plate of the CSU printed wiring card, shown in FIG. 3. 
LEDs 250 includes the local alarm LED mentioned above. In addition, LEDs 
250 include an active lamp, a modem lamp and a power on lamp. The active 
lamp indicates that the CSU is in active operation. The signal lighting 
this lamp is generated by software command during normal CSU operation. 
The modem lamp indicates that the modem port of the CSU is in use. This 
signal is generated by software of the CSU, when it is interfacing with 
the remote CRT via the modems. The power on light indicates that each of 
the three voltages (+12 volts, -12 volts and +5 volts) is being provided 
to the CSU. The power on light is turned-off when the +5 volt or +12 volt 
power supply is reduced to a zero voltage level or when the -12 volt power 
supply drops below a -6 volt level. 
Switches 260 are momentary pushbutton switches for reset and self test 
functions. The reset pushbutton causes microcontroller 200 and associated 
latching circuitry to be reset. The self test pushbutton enables the 
microcontroller 200 to perform predefined self test routines in response 
to an interrupt signal generated by pushing of the self test pushbutton. 
The DC to DC converter 270 produces +12 volts, -12 volts and +5 volts from 
either a -48 volt source or a -24 volt source. 
FIG. 3 depicts the CSU face plate. Four lamps or LEDs are shown for each of 
the above mentioned functions. In addition, two momentary pushbutton 
switches and a 25 pin RS-232-C connector for connecting the local CRT to 
the CSU are shown. 
Although the preferred embodiment of the invention has been illustrated, 
and that form described in detail, it will be readily apparent to those 
skilled in the art that various modifications may be made therein without 
departing from the spirit of the invention or from the scope of the 
appended claims.