Function Code 16 (Preset Multiple Register); Error Messages - Samson Trovis 6400 Mounting And Operating Instructions

Interface RS-485
Response from the process control station
Address Function
11 0F
The master only writes to coils that are marked with R/W. When attempts are made to write to
Read-Only coils, no error message is issued by the process control station. The Modbus
response is sent while the Write command is still being carried out. It is therefore possible that
any following Write commands are answered with error code 6 ("Busy").

9.5.8. Function code 16 (Preset Multiple Register)

This function code is used to modify values of multiple holding registers.
Example: Two holding registers, starting at address 135, are sent to the process control station
with the device address 17.
Query from the central control station
Address Function
high
11 10
The value 10 (corresponds to 000A
(corresponds to 0102
Response from the process control station
Address Function
11 10
The master only writes to coils that are marked with R/W. When attempts are made to write to
Read-Only coils, no error message is issued by the process control station. The Modbus
response is sent while the Write command is still being carried out. It is therefore possible that
any following Write commands are answered with error code 6 ("Busy").

9.5.9. Error messages

The process control station responds with an error message upon illegal operations between
the control station (Modbus-Master) and the process control station (Modbus slave):
– Error code 01: Illegal function requested
– Error code 02: Query containing an undefined data address
– Error code 03: Query containing an illegal data value
– Error code 06: Query while the process control station is busy, COPA pin or COPA
adapter with software TROVIS 6482 are being used ("Busy" message)
Coil address
high low
00 13
Address Quant. holding reg.
low high
00 87 00
) is placed into holding register 13 and the value 258
H
) is placed into holding register 136.
H
Coil address
high low
00 87
Functions supported by the Modbus protocol
Quantity of coils
high
00
Byte 1 data value 2 data value
count field
low high
02 04 00
Quantity of coils
high
00
CRC
low low
0A 26
low high low low
0A 01 02
CRC
low low
02 F3
high
99
CRC
high
4E BA
high
71
65