ICP DAS USA M-7065 User Manual page 108

Response:
00 Address
01 Function code
02 Byte Count
03~ Register values
Error Response:
00 Address
01 Function code
02 Exception code
Examples:
Command:05 04 01 E2 00 02 [ D1 85 ]
Response:05 04 04 20 60 00 00 B5 9A
Reads module's name
Command:01 04 01 E4 00 01 [ 70 01 ]
Response:01 04 02 00 01 78 F0
Reads address of modules
Command:01 03 00 00 00 02 [ C4 0B ]
Response:01 03 04 00 15 00 15 2A 38
Reads DI count of modules
M-7065 User's Manual Ver2.0, Dec. /200 8 ---108
1 Byte
1 Byte
Byte count of response
1 Byte
(B=2 * word count)
(B*2) Byte
1 Byte
1 Byte
Refer to Modbus standard
1 Byte
1-247
0x04
Register values
1-247
0x83
for more details