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A Appendices
E5@D Digital Temperature Controllers Communications Manual (H225)
A
-2 T
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ub
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A
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.
Item
Confirmation
Page
The communications wiring is not
correct.
Correct the wiring.
1-4
The communications line has
become disconnected.
Connect the communications line securely and tighten the
screws.
---
The communications cable is
broken.
Replace the cable.
---
The communications cable is too
long.
The total cable length is 500 m maximum for RS-485
communications.
1-4
The wrong communications cable
has been used.
Use shielded twisted-pair cable for the communications
cable. For detailed wiring specifications, refer to
Precautions for Safe Use
on page 7.
1-4
Too many communications
devices are connected to the
communications path.
When 1:N, RS-485 communications are used, a maximum
of 32 nodes may be connected, including the host node.
1-4
An end node has not been set at
each end of the communications
line.
Set or connect terminating resistance at each end of the
line. If the E5
@
D 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.
1-4
The specified power supply
voltage is not being supplied to
the Controller.
Supply the specified power supply voltage.
---
The specified power supply
voltage is not being supplied to
an Interface Converter (e.g., the
K3SC).
Supply the specified power supply voltage.
---
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.
Set the same values for the following on all nodes: baud
rate, protocol, data length, stop bits, and parity.
1-2
The unit number specified in the
command frame is different from
the unit number set for the
Controller.
Use the same unit number.
2-2
4-2
The same unit number as the
Controller is being used for
another node on the same
communications line.
Set each unit number for only one node.
1-7
There is a mistake in
programming in the host device.
Use a line monitor to check the commands.
---
The host device is detecting the
absence of a response as an
error before it receives the
response from the Controller.
Shorten the send data wait time in the Controller or
increase the response wait time in the host device.
1-7
Summary of Contents for E5 D Series
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