Rockwell-automation 57C442 Data Highway Plus Interface Module Manual de usuario descargar pdf (Pagina 13)

2-3

2.2 Electrical Description

The Data Highway Plus Interface module contains an 8 MHz

microprocessor that shares 32K of dual port memory with the AutoMax

rack backplane. This memory is accessible to both the on-board

microprocessor and AutoMax Processors in the rack. A block diagram

is shown in Appendix B. The module contains a watchdog timer which

is enabled when power is turned on to the module. The microprocessor

must reset the watchdog timer within a specified time or the

microprocessor will shut down and the status LED labeled ”OK” on the

faceplate will turn off.

At power-up, the on-board microprocessor runs diagnostics on the

microprocessor, EPROM, RAM and dual port memory, as well as

performing system-level diagnostics. As each test is run, a number is

written out to the seven-segment display. If there is a fault during these

tests, the microprocessor halts, the watchdog times out, and the seven-

segment LED displays the code of the failed diagnostic. See Appendix

D for a list of error codes.

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Rockwell-automation 57C442 Data Highway Plus Interface Module Manual de usuario Pagina 13