User Guide

FS-8704-16 Omron FINS Manual Page 36 of 37
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Therefore the PLC responds to 192.168.0.34 which is clearly the wrong address
and the FieldServer will not see the response.
Example: - Class A Addressing
A FieldServer with IP address=192.168.1.81 and system_node_id=34 polls for
data from a PLC with IP address =192.168.2.33 and Subnet mask = 255.255.0.0
The PLC responds to 192.168.2.33
255.0.0.0
192.x.x.y
Where x is always set to zero and
y is equal to 34 (The PLC obtains the node ID of 34 by
inspecting the contents of the poll message.)
Therefore the PLC responds to 192.0.0.34 which is clearly the wrong address
and the FieldServer will not see the response.
Thus, if the PLC is using Class A/B IP addressing then the 3
rd
(Class B) or the
2nd and 3rd (Class A) bytes of the address must be zero as must the
FieldServer's if communications are to work.
There are ways around this problem, we believe. The solution requires usage of
the Omron PLC routing table. For more help consult with Omron's Tech Support.