Dwyer UXF3 - Manual (Page 15)

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5.4 Function Code
According to MODBUS protocol, register numbers are assigned by function codes.
Each function code acts on specific register number.
This correspondence is shown in Table 5-2, and the message length by function is shown in Table 5-3.
Table 5-2 Correspondence between function codes and objective address
Function code Resister No.
No. Function Object No. Contents
03
H
Read-out
(continuously)
Holding register 4xxxx Read-out/write-in word data
04
H
Read-out
(continuously)
Input register 3xxxx Read-out word data
06
H
Write-in Holding register 4xxxx Read-out/write-in word data
10
H
Write-in
(continuously)
Holding register 4xxxx Read-out/write-in word data
Table 5-3 Function code and message length
[Unit:byte]
Command message Response message
Function
code
Contents
Number of
designatable
data
Minimum Maximum Minimum Maximum
03
H
Read-out of word data 64 words 8 8 7 133
04
H
Read-out of word data
(read-out only)
64 words 8 8 7 133
06
H
Write-in of word data 1 word 8 8 7 7
10
H
Write-in of continuous word data 64 words 11 137 8 8