Read Holding Register Response; Force Single Coil - Function Code 05; Force Single Coil Query; Force Single Coil Response - ABB C1900 Installation Manual

...5 MODBUS FUNCTIONS

5.2.2 Read Holding Register Response

The addressed slave responds with its address and function code, followed by the information field. The information field contains
1 byte describing the quantity of data bytes to be returned. The contents of each register requested (DATA) is two bytes, the first
byte includes the high order bits and the second the low order bits.
– the response to the read holding register query shows the following:
Example
Alarm trip A1 –
Alarm trip B1 –
Alarm trip C1 –
Alarm trip D1 –
Alarm trip A2 –
Alarm trip B2 –
Byte
Address Function
Count
01 03 0C
5.3 Force Single Coil – Function Code 05

5.3.1 Force Single Coil Query

This message forces a single coil either ON or OFF. The data value 65,280 (FF00 HEX) sets the coil ON and the value zero turns
it OFF. All other values are illegal and do not affect the coil.
Note. To write to a coil the coil offset address must be used, e.g. to write to coil 149, the coil address 148(94H) is transmitted.
The use of slave address zero (broadcast mode) forces all attached slaves to modify the desired coil.
– a force single coil request to switch ON coil address 149 (auto/manual state, channel 1) in slave 01 is shown below.
Example
Address Function
01 05

5.3.2 Force Single Coil Response

The response is confirmation of the query after the coil state has been altered.
:
Example
Address Function
01 05
10
150
50
100
400
0
0
Holding Holding
Register 121 Register 122
High Low High Low
00 96 00 32
Coil Offset Coil Offset
High Low
00 94
Coil Offset Coil Offset
High Low
00 94
Holding Holding
Register 123 Register 124
High Low High Low
00 64 01 90
Data Value High Data Value Low
FF
Data Value High Data Value Low
FF
Holding Holding
Register 125 Register 126
High Low High Low
00 00 00 00
Error Check Field (CRC-16)
00 CD
Error Check Field (CRC-16)
00 CD
Error Check Field
(CRC-16)
D9 91
D6
D6