GE Industrial Solutions MX350 Communications Guide - Manual (Page 9)

COMMUNICATIONS GUIDE RS485 INTERFACE (MODBUS RTU)
MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – COMMUNICATIONS GUIDE 5
Modbus Functions
Function Code 01H Modbus implementation: Read Input Status
MX350 implementation: Read Net Control Status
This function code is supported for a selective range of commands for MX350 for net
control functionality. This function reads the ON/OFF status for each net control
command. The query message specifies the starting command and number of commands
status to be read. Commands are addressed starting at zero.
The master/slave packets have the following format:
Table 1: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 03H
Each returned data bit is an ON/OFF status. The number of returned data bytes will
change according to the number of points requested.
The following table lists the supported command addresses for this function code:
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave 17
FUNCTION CODE 1 02 read net control status
STARTING ADDRESS 2 00 C4 starting command address
NUMBER OF POINTS 2 00 02 number of status bits
CRC 1 CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from slave 17
FUNCTION CODE 1 02 read net control status
BYTE COUNT 1 01 number of status bytes
DATA 1 1 bytes of net control status
CRC 1 CRC error code