YOKOGAWA IR202, User Manual

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<3. MODBUS PROTOCOL>
3-3
IM 11G02Q02-01EN 2nd Edition : Sep. 04, 2020-00
(3) No response
Under any of the following conditions, the slave station takes no action to the command message
and sends back no response.
• A station number transmitted in the command message differs from the Station No. (station
number) specified to the slave station.
• An error check code is not matched, or a transmission error (parity error, etc.) is detected.
• The time interval between the composition data of the message becomes longer than the
time corresponding to 24 bits. (Refer to “”)
3.3 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 3-2, and the message length by function is shown in
Table 3-3.
Table 3-2 Correspondence between function codes and objective address
Function code ←→ Register No.
No. Function Object No. Description
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-pit / wrote in word data
10
H
Write-in (continuously) Holding register 4xxxx Read-out / write-in word data
Table 3-3 Function code and message length (Unit : byte)
Function
Code
Contents Number of
designatable data
Command message Response message
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 8 8
10
H
Write-in of continuous
word data
64 words 11 137 8 8