GE Power Management
MM2 Motor Manager 2 6-5
6 COMMUNICATIONS 6.2 MODBUS FUNCTIONS
6
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
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