Basler Electric DECS-400 - Manual (Page 220)

208 9369700990 Rev R
Query message format is:
Device Address
Function Code = 10 (hex)
Starting Address High
Starting Address Low
Number of Registers High (total number of registers to be loaded)
Number of Registers Low
Byte Count (total number of registers to be loaded times 2)
Data High
Data Low
Data High
Data Low
CRC Error Check (Lo, Hi)
Note: Max. length of Preset Multiple Registers Query is 9 + (100 x 2) = 209 bytes.
Response
The response message echoes the starting address and the number of registers. There is no response
message when the query is a broadcast (device address of 0).
Device
Address
Function
Code =
10 (hex)
Starting
Address
High
Starting
Address
Low
Number of
Registers
High
Number of
Registers
Low
CRC
Low
CRC
High
Preset Single Register (Write Single Holding Register)
A Preset Single Register query message requests a single register to be written. The DECS-400 will
perform the write when the device address is the same as the DECS-400 remote address.
Query
Device Address
Function Code = 06 (hex)
Address Hi
Address Lo
Data Hi
Data Lo
CRC Hi error check
CRC Lo error check
Response
Normal Response
The response message echoes the Query message after the register has been altered.
Error Response
Data will cease to be written if any of the following exceptions occur.
•
Queries to write to the Read Only registers result in an error response with Exception Code of
“Illegal Data Address”.
•
A query to write an illegal value (out of range) to a register results in an error response with
Exception Code of “Illegal Data Value”.
There are several instances of registers that are grouped together to collectively represent a single
numerical DECS-400 data value, e.g., floating point data and 32-bit integer data. A query to write a
subset of such a register group will result in an error response with Exception Code “Illegal Data
Address”.
Modbus™ Communication DECS-400