GE Industrial Solutions MX350 Communications Guide - Manual (Page 16)

12 MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – COMMUNICATIONS GUIDE
RS485 INTERFACE (MODBUS RTU) COMMUNICATIONS GUIDE
CRC: 2 bytes
The MX350 implements the following exception response codes:
01 - ILLEGAL FUNCTION
The function code transmitted is not one of the functions
supported by the MX350.
02 - ILLEGAL DATA ADDRESS
The address referenced in the data field transmitted by the
master is not an allowable address for the MX350.
03 - ILLEGAL DATA VALUE
The value referenced in the data field transmitted by the
master is not within range for the selected data address.
Performing commands using Function Code 10H
All commands other than net control commands can be performed using function code 16
as well as function code 5. When using FUNCTION CODE 16, the Command Function
register must be written with a value of 5. The Command Operation register must be
written with a valid command operation number. The Command Data registers must be
written with valid data; this is dependent upon the command operation.
For example, consider a request for slave 17 to perform command operation 1 (RESET): The
master/slave packets have the following format:
Table 8: MASTER/SLAVE PACKET FORMAT FOR PERFORMING COMMANDS
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave 17
FUNCTION CODE 1 10 store multiple
setpoints
DATA STARTING ADDRESS 2 00 80 setpoint address 00
80
NUMBER OF SETPOINTS 2 00 02 2 setpoints = 4 bytes
total
BYTE COUNT 1 04 4 bytes of data
DATA 1 2 00 05 data for address 00
80
DATA 2 2 00 01 data for address 00
81
CRC 2 7E CE CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from slave
17
FUNCTION CODE 1 10 store multiple
setpoints
DATA STARTING ADDRESS 2 00 80 setpoint address 00
80
NUMBER OF SETPOINTS 2 00 02 2 setpoints
CRC 2 42 B0 CRC error code