Modbus Functions; Function Code 01H - GE MOTOR MANAGER 2 Instruction Manual

6 COMMUNICATIONS

6.2 MODBUS FUNCTIONS

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:
Table 6–1: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 01H
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
OPERATION STARTING ADDRESS
NUMBER OF OPERATIONS TO READ
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
BYTE COUNT
DATA 1 (see definition below)
CRC
The DATA 1 definition is as follows:
Data 1 = 08 (hex) =
command operation #
GE Power Management
BYTES
1
1
2
2
2
BYTES
1
1
1
1
2
0 0 0 0
N/A N/A 15 14
MM2 Motor Manager 2
6.2 MODBUS FUNCTIONS

6.2.1 FUNCTION CODE 01H

EXAMPLE DESCRIPTION
11 message for slave 17
01 read last command operation
00 0A start at operation 10
00 06 read 6 operations
9E 9A CRC error code
EXAMPLE DESCRIPTION
11 message from slave 17
01 read last command operation
01 6 operations = 6 bits: only 1 byte required
08 bit set corresponding to command 13
54 83 CRC error code
1 0 0
13 12 11
0
10
6-5
6