Troubleshooting - Omron E5CC Communications Manual

A-2 Troubleshooting
Before Requesting Repairs
If communications are not functioning properly, check the items in the following table before requesting
repairs. If normal operation cannot be restored even after checking everything, return the product to
your OMRON representative.
Problem: Communications are not possible or communications errors occur.
The communications wiring is not
correct.
The communications line has
become disconnected.
The communications cable is
broken.
The communications cable is too
long.
The wrong communications cable
has been used.
Too many communications
devices are connected to the
communications path.
An end node has not been set at
each end of the communications
line.
The specified power supply
voltage is not being supplied to
the Controller.
The specified power supply
voltage is not being supplied to
an Interface Converter (e.g., the
K3SC).
The same baud rate and
communications method are not
being used by all of the
Controllers, host devices, and
other nodes on the same
communications line.
The unit number specified in the
command frame is different from
the unit number set for the
Controller.
The same unit number as the
Controller is being used for
another node on the same
communications line.
There is a mistake in
programming in the host device.
The host device is detecting the
absence of a response as an
error before it receives the
response from the Controller.
E5@C Digital Temperature Controllers Communications Manual (H175)
Item
Correct the wiring.
Connect the communications line securely and tighten the
screws.
Replace the cable.
The total cable length is 500 m maximum for RS-485
communications.
Use shielded twisted-pair cable for the communications
cable. For detailed wiring specifications, refer to
Precautions for Safe Use on page 7.
When 1:N, RS-485 communications are used, a maximum
of 32 nodes may be connected, including the host node.
Set or connect terminating resistance at each end of the
line. If the E5@C is the end node, 120-Ω (1/2-W)
terminating resistance is used. Be sure that the combined
resistance with the host device is 54 Ω minimum.
Supply the specified power supply voltage.
Supply the specified power supply voltage.
Set the same values for the following on all nodes: baud
rate, protocol, data length, stop bits, and parity.
Use the same unit number.
Set each unit number for only one node.
Use a line monitor to check the commands.
Shorten the send data wait time in the Controller or
increase the response wait time in the host device.
A Appendices
Confirmation Page
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