Instruction Manual

Table 6-10. Error Code Bytes for PCS Modbus Slave
Title Definition DDI-A DDI-B Set
By
De-
fault
Exception Response
Code*
Exception Response Codes 1-3 are sent
from the PCS slave to the Modbus
master.
01 - Illegal Function: Does not exist as a
valid function code.
02 - Illegal Data Address: Not an allow-
able address for the specified slave
location (L address over L2047 or C
address over C767).
03 - Illegal Data Value: The data value is
not allowable in the slave (the fetch
quantity requested of a PCS slave
exceeded 512 L-values or 64
C- values).
B671 B647 Soft-
ware
0
Communications
Error*
0 = no errors. 254 = bad checksum
(CRC) - a bad checksum indicates even
though the frame was formatted
properly, the data can not be used. 253
= bad message - bad message indicates
that errors were found in the predictable
portion of the message from the master
device. 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.
Section 6. MODBUS RTU Mode
MODBUS2
6-17