External device setup manual – IDEC High Performance Series User Manual
Page 641

623
1 Modbus
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Modb
us
External Device Setup Manual
- FC1 Read coils - Reading of Coil (C) consecutively
Normal response
Byte 7
FC (Function code) = 10(HEX)
Byte 8-9
Reference No.
From Byte 10
Number of write words
Abnormal response
Byte 7
FC (Function code) = 90 (HEX)
Byte 8
Exception code 01 or 02
Example
Writing to HR400001 (1 word). The write value is 1234 (HEX).
10 00 00 00 01 02 12 34 => 10 00 00 00 01
Request
Byte 7
FC (Function code) = 01
Byte 8-9
Reference No.
Byte 10-11
Number of read bits (1 to 2000 bits)
Normal response
Byte 7
FC (Function code) = 01
Byte 8
Number of bytes for the response ((number of read bits +7)/8)
From Byte 9
Read data
Abnormal response
Byte 7
FC (Function code) = 81 (HEX)
Byte 8
Exception code 01 or 02
Example
Reading of C1. 1 bit. The read value is 1.
01 00 00 00 01 => 01 01 01