Read Holding Register Response; Force Single Coil; Force Single Coil Query; Force Single Coil Response - ABB 8241 Operating Instructions Manual

...8 MODBUS FUNCTIONS

8.2.2 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.
Example – the response to the read holding register query shows the following:
Time (Hour) = 15
Time (Minutes) = 20
Time (Date) = 25
Time (Month) = February
Address Function Byte Count
01 03
8.3 Force Single Coil – Function Code 05

8.3.1 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 10, the coil address 09(09H) is
transmitted.
The use of slave address zero (broadcast mode) forces all attached slaves to modify the desired coil.
Example – a force single coil request to switch ON coil address 10 (NV Memory Save) in slave 01 is shown below.
Address
Function
01 05

8.3.2 Force Single Coil Response

The response is confirmation of the query after the coil state has been altered.
Example:
Address
Function
01 05
Holding
Register 11
High Low
08 00 0F
Coil Offset Coil Offset
High Low
00 09
Coil Offset Coil Offset
High Low
00 09
Holding Holding
Register 12 Register 13
High Low High Low
00 14 00 19
Data Value High Data Value Low
FF 00
Data Value High Data Value Low
FF 00
Holding
Error Check Field
Register 14
(CRC-16)
High Low
00 02 0A D2
Error Check Field (CRC-16)
5C 38
Error Check Field (CRC-16)
5C 38
9