KROHNE ALTOSONIC V Modbus EN - Manual (Page 12)

ALTOSONIC V
ModBus Manual 0300 rev07 E 7.30855.35.00 Page 12 of 64
5.4 Function 04: READ INPUT REGISTERS
In the UFP-V Modbus protocol, function 3 and 4 perform the same processing and are
interchangeable.
5.5 Function 05: WRITE SINGLE COIL
Description
Function 5 forces a single coil to either ON or OFF (0x reference).
When the address is a broadcast, all slaves will process the request.
Query
The query message specifies the coil reference to be forced. Coils are addressed starting at zero (coil
1 is addressed as zero).
The requested ON/OFF status is specified by a constant in the query data field. A value of FF 00 hex
requests the coil to be ON. A value of 00 00 requests it to be OFF. All other values are illegal and do
not affect the coil and generate an exception.
Example
Here is an example of a request to force coil 173 ON in slave device 17.
Coil Address Data Header
--
Slave
Address
11(h)
Function
05(h) Hi
00(h)
Low
AC(h)
Hi
FF(h)
Low
00(h)
Error
Check
--
Trailer
--
The normal response is an echo of the query, returned after the coils state has been forced.
Coil Address Data Header
--
Slave
Address
11(h)
Function
05(h) Hi
00(h)
Low
AC(h)
Hi
FF(h)
Low
00(h)
Error
Check
--
Trailer
--
If the request is not applicable an exception response will be sent.
See chapter 5.10 for exception responses.
5.6 Function 06: WRITE SINGLE HOLDING REGISTER
Description
Function 6 pre-sets a value into a single holding register (4x reference).
When the address is a broadcast, all slaves will process the request.
Query
The query specifies the register reference to be preset. Registers are starting at address zero.
The requested value (preset) is specified in the query data field, which is a 16-bit value.