Micromod Micro-DCI: 53MC5000 PLC AND PRINTER INTERFACES - Manual (Page 74)

Table 6-4. Read Control Bytes for PCS Modbus Master
Title Definition DDI-A DDI-B Set
By
De-
fault
PLC Error Code*
(Exception Response
Code) Exception Response Codes 1-7 can be sent
from the PLC to the PCS master (see the
Modbus documentation for complete
definitions.)
01 - Illegal Function: Does not exist as a
valid function code.
02 - Illegal Data Address: Not an allowable
address.
03 - Illegal Data Value: The fetch quantity
requested is not allowed.
04 - Failure In Associated Device: The
slave failed to respond to the message.
05 - Acknowledge: The slave has accepted
and is processing a long duration
command. B671 B647 Soft-
ware 0
06 - Busy, Rejected Message: The slave is
busy processing a long duration com-
mand.
07 - NAK, Negative Acknowledgement: The
program function just requested can not
be performed.
Communications
Error* 0 = no errors. 255 = timeout error - a
timeout error indicates no response came
back from the PLC. 254 = bad checksum
(CRC) - a checksum indicates even though
the frame was formatted properly, the data
can not be used. 253 = bad message - bad
message indicates unexpected data was
found in the reply from the PLC. 252 and
251 = PCS hardware malfunction. B672 B648 Soft-
ware 0
Error Count* This byte is a running total of the Exception
Response Codes and the Communication
Errors listed above. B673 B649 Soft-
ware 0
*User can reset by writing zeros into the datapoints.
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53MC9015 53MC5000 PLC and Printer Interfaces
6-10
MODBUS2