Fuji Electric ALPHA7, User Manual

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CHAPTER 13 MODBUS RTU COMMUNICATION
Transmission Protocol
13-13
13
<Response message example>
Station No. 1 byte
01
FC 1 byte 05
Information
Address
2 bytes
02
08
No. of coil data 2 bytes
FF
00
CRC check
16 bits
(2 bytes)
0C
40
 FC 0Fh (Write in coil data)
(1) Query from the master
Station No. 1 byte
FC 1 byte ･･･
0Fh
Information
Address 2 bytes
(H)
･･･
Specify the coil address.
* For the addresses, refer to the table 13-2.
(L)
No. of coil data
2 bytes
(H)
･･･
Specify the number of coils n.
* Up to 16 pcs.
(L)
No. of data bytes 1 byte
･･･
The value (N) obtained from n/8 and by
rounding up decimal
Data 1
1 byte (8 bits)
･･･
n pcs of data read out from a specified address.
* 1 pcs = 1 bit (1 byte by 8 pcs)
* Allocated from LSB in order.
~ ~
Data N 1 byte (8 bits)
CRC check
16 bits
(2 bytes)
(L)
(H)
(2) Response message from the amplifier
Station No. 1 byte
FC 1 byte ･･･
05h
Information
Address
2 bytes
(H)
･･･
Specified address.
(L)
No. of coil data 2 bytes
(H)
･･･
The number of coils actually written in is m pcs.
* Cannot write in to nonexistent coil data.
(L)
CRC check
16 bits
(2 bytes)
(L)
(H)