Micromod Micro-DCI: 53MC5000 PLC AND PRINTER INTERFACES - Manual (Page 83)

6.5.5 PCS MODBUS SLAVE FAULT ISOLATION AIDS
Table 6-11 summarizes information provided in this section and other sections of the book that can
be referenced as an aid to fault isolation.
Table 6-11. Modbus Slave Fault Isolation Aids
Environmental/Power
See Table 1-1 for RS-232/485 ITB environmental and power specifications; see 53MC5000 PCS
Instruction Bulletin for PCS environmental and power specifications.
PCS Setup Errors
Setup Error 10 (Table 6-9) - Set Scan Time to non-zero value. PCS APB Setup bytes (Table 6-
8) - Should agree with the communication setup of the master device system.
Scan Overrun Counter (Table 6-9 and Section 3.7) - Expand Scan Time if the count increases at
an unacceptable rate.
Communications
Proper cable fabrication between the RS-232/485 ITB and the master device (Figures 6-2 and 6-
3). Communication Error and Error Count (Table 6-10) - Execute the Diagnostic command
(Function code = 8) from the master device to the PCS Modbus slave to test the communications
link.
Possible PLC Problems
Reference the appropriate PLC documentation for the required action.
Exception Response Codes 1-3 (Table 6-10) - Check Function, Data Address, and Data Values in
master device commands being sent to PCS Modbus slave.
RS-232/485 ITB Activity Indicators
Inactivity from the XMT (CR13) and RCV (CR14) LEDs could indicate line problems, a hung
device, a misconfiguration between the PCS and master device resulting from manual database
alterations made at either device, or just no DDI channel activity. Active indicators on the RS-
232/485 ITB do not necessarily mean error free operation, e.g., repeated PCS-master device
transactions attempted with timeout errors.
Section 6. MODBUS RTU Mode
MODBUS2
6-19