15
5
MODBUS FUNCTIONS…
5.6
Force Multiple Coils – Function Code 15
5.6.1
Force Multiple Coils Query
This message is used to force up to 32 coils at a time to the ON or OFF state. When used with slave
address zero (broadcast mode) all slave controllers force the selected coils to the state(s) specified.
Note. To write to a coil, its offset address (one less than the register number) must be used,
e.g. to write to coil 39, the offset address 38 (26H) is transmitted.
Example. Force coil 39 to ON (Select manual mode) and coil 40 to OFF (Select Local Set Point
mode).
5.6.2
Force Multiple Coils Response
The Force Multiple Coils Response confirms slave identification, function code, starting register
address and quantity only.
Example
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9
