MVI56E-MCMR ♦ ControlLogix Platform
Verify Communication
Modbus Communication Module with Reduced Data Block
User Manual
ProSoft Technology, Inc.
Page 111 of 223
Module Communication Error Codes
Code
Description
-1
CTS modem control line not set before transmit
-2
Timeout while transmitting message
-11
Timeout waiting for response after request
253
Incorrect Slave address in response
254
Incorrect function code in response
255
Invalid CRC/LRC value in response
"Module Communication Errors" are generated by the MVI56E-MCMR module,
and indicate communication errors with the Slave device.
Error Code -11 indicates that the module is transmitting a message on the
communications wire. However, it is not receiving a response from the addressed
Slave. This error is typically caused by one or more of the following conditions.
Parameter mismatch, for example the module is set for 9600 baud, Slave is
set for 19,200, parity is set to none, Slave is expecting even, and so on.
Wiring problem, for example the port jumper on the module is set incorrectly,
or + and - lines on RS485 are switched)
The Slave device is not set to the correct address, for example the Master is
sending a command to Slave 1 and the Slave device is configured as device
10.
With a -11 error code, check all of the above parameters, wiring, and settings on
the Slave device. Also, make sure that you cycle power to the module, or toggle
the
MCMR.CONTROL.W
ARM
B
OOT
or
C
OLD
B
OOT
bit.
Error codes of 253 to 255 typically indicate noise on RS485 lines. Make sure that
you are using the proper RS485 cable, with termination resistors installed
properly on the line. If termination resistors are installed, try removing them, as
they are usually only required on cable lengths of more than 1000 feet.
Command List Entry Errors
Code
Description
-41
Invalid enable code
-42
Internal address > maximum address
-43
Invalid Modbus Slave Device Address (< 0 or > 255)
-44
Count parameter set to 0
-45
Invalid function code
-46
Invalid swap code
The above error codes indicate that the module has detected an error when
parsing the command.
For all commands that have not been configured (all parameters set to a value of
0) you will receive an error code of -44. To remove this error code, you can
change your
M
ODBUS
P
ORT X
R
EG
C
OUNT
parameter to the number of registers to
send, and download the updated configuration to the module.
