Rockwell Automation 57C428 Toledo Scale Interface Module - Manual (Page 9)

2Ć1
2.0 MECHANICAL/ELECTRICAL
DESCRIPTION
The following is a description of the faceplate LEDs, field termination
connectors, and electrical characteristics of the field connections.
2.1 Mechanical Description
The Toledo Scale Interface module is a printed circuit board
assembly that plugs into the backplane of the DCS5000/AutoMax
rack. It consists of a printed circuit board, a faceplate, and a
protective enclosure. The faceplate contains tabs at the top and
bottom to simplify removing the module from the rack. Module
dimensions are listed in Appendix A.
The faceplate of the module contains a 25 pin D" shell connector for
an RSĆ232C serial I/O link. For diagnostic purposes, the faceplate
contains one sevenĆsegment LED and a green status light that
indicates when the board is operational (ON) or malfunctioning
(OFF). There are also two thumbwheel switches on the faceplate of
the module. These switches are not used in this application. See
figure 2.1.
The back of the module contains two edge connectors that attach to
the system backplane.
2.2 Electrical Description
The interface module contains a 4 mhz Z80 microprocessor.
Processor memory consists of 16K bytes of EPROM memory for the
communication software, 8K bytes of RAM for local data storage, and
4K words of dual port memory. The module is equipped with a
RSĆ232C serial I/O port, a programmable baud rate generator, and
the necessary circuitry to interface with the system backplane. Refer
to the block diagram in Appendix B.
This module also contains a watchdog timer, used to detect hardware
failures. The watchdog is enabled whenever power is turned on to
the module. If a processor is unable to reset the watchdog, an
interrupt will be generated to stop the processor. The dual port
memory will be disabled so that it cannot be accessed by the user's
application software.
There is one green status light and one 7Ćsegment LED on the
faceplate of the module. The status light is labeled OK". When the
light is on, the module has passed its powerĆup diagnostics and the
watchdog timer has not timed out.