Teledyne 7600 - Infrared gas analyzer - communication manual - Manual (Page 11)

Teledyne Analytical Instruments
11
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
60 words 8 8 7 133
04
H
Read-out of
word data
(read-out
only)
15 words 8 8 7 133
06
H
Write-in of
word data
1 word 8 8 8 8
10
H
Write-in of
continuous
word data
60 words 11 137 8 8