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GE Power Management

MM2 Motor Manager 2 6-5

6 COMMUNICATIONS 6.2 MODBUS FUNCTIONS

6.2 MODBUS FUNCTIONS 6.2.1 FUNCTION CODE 01H

Modbus implementation: Read Coil Status

MM2 implementation: Read Last Command Operation

This function code allows the master to read back which command operation was last performed

using Modbus function code 05: force single coil/execute operation. Upon request of coil/operation

status, the MM2 will set a bit corresponding to the last operation performed. The operation com-

mands are in the Modbus Data Formats table under code F22.

Note: Operation 0 will be set (1) if no operations have been performed since the MM2 has been pow-

ered up.

For example, a request slave 17 to respond with status of 6 operations, starting at operation 10, after

performing command operation 13 (Manual Inhibit) has the following format:

The DATA 1 definition is as follows:

Table 6–1: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 01H

MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION

SLAVE ADDRESS 1 11 message for slave 17

FUNCTION CODE 1 01 read last command operation

OPERATION STARTING ADDRESS 2 00 0A start at operation 10

NUMBER OF OPERATIONS TO READ 2 00 06 read 6 operations

CRC 2 9E 9A CRC error code

SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION

SLAVE ADDRESS 1 11 message from slave 17

FUNCTION CODE 1 01 read last command operation

BYTE COUNT 1 01 6 operations = 6 bits: only 1 byte required

DATA 1 (see definition below) 1 08 bit set corresponding to command 13

CRC 2 54 83 CRC error code

Data 1 = 08 (hex) =

00001000

command operation #

N/A N/A 15 14 13 12 11 10

GE MOTOR MANAGER 2 User Manual

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