Winco DGC-2020 - Manual (Page 281)

9400200990 Rev K DGC-2020 Modbus
 Communication
B-5
 There are several instances of registers that are grouped together (signified as DP or TP) to
collectively represent a single numerical (vs. ASCII string) DGC-2020 parameter value. A query to
write a subset of such a register group will result in an error response with Exception Code “Illegal
Data Address”.
 A query to write an unallowed value (out of range) to a register results in an error response with
Exception Code of “Illegal Data Value”.
Device Address
Function Code
06 (hex)
Address Hi
Address Lo
Data Hi
Data Lo
CRC Error Check
RESPONSE:
The response message echoes the address and the value written. There is no response message when
the query is broadcast.
Device Address
Function Code
06 (hex)
Address Hi
Address Lo
Data Hi
Data Lo
CRC Error Check
DATA FORMATS
Short Integer Data Format (INT8)
The Modbus short integer data format uses a single holding register to represent an 8 bit data value. The
holding register high byte will always be zero.
Example: The value 132 represented in short integer format is hexadecimal 0x84. This number will read
from a holding register as follows:
Holding Register
Value
K (Hi Byte) hex 00
K (Lo Byte) hex 84
The same byte alignments are required to write.
Integer Data Format (INT16)
The Modbus integer data format uses a single holding register to represent a 16-bit data value.
Example: The value 4660 represented in integer format is hexadecimal 0x1234. This number will read
from a holding register as follows:
Holding Register
Value
K (Hi Byte) hex 12
K (Lo Byte) hex 34
The same byte alignments are required to write.