49
4. Troubleshooting Based on Error Symptoms
If the cause of the error is still unknown after checking all the previously men-
tioned items, find the cause by isolating the symptoms of the error while re-
ferring to the tables in this section, and remedy accordingly.
4-2
Communications Errors
Communications Not Possible or No Response
Probable cause
Remedy
Communications
conditions
Baud rate of the E5ZE is different from that of
the host device.
Set the same rate.
Communications method of the E5ZE is different
from that of the host device.
Set the host device’s communications conditions
as follows:
•
Stop bits:
2
•
Parity:
Even
•
Bit length: 7 bits
Connections
Excessive number of E5ZE Units are connected
in parallel.
Do not connect an excessive number of E5ZE
Units.
•
Do not connect the host device directly to more
than one E5ZE through RS-232C
communications.
•
The number of E5ZE Units that can be
connected to the host device for RS-422 or
RS-485 communications is 16 max.
Transmission path is too long.
The transmission path must be within the
permissible range.
•
The maximum RS-232C transmission path is
15 m.
•
The maximum RS-422 or RS-485 transmission
path is 500 m in total.
Same unit number has been assigned more than
once on the same transmission path.
Make sure that different numbers are assigned
to all the E5ZE Units that communicate with the
host device.
Communications data error due to ambient
noise.
•
Move the communications cable away from the
source of noise.
•
Use shielded communication cables.
•
Use an Optical Interface.
•
Write a program that makes it possible for the
host device to detect a response error for any
command that the host device transmits and to
re-transmit it again.
Mistake in the use of the Optical Interface and
Link Adapter Units.
Refer to the datasheets of the Optical Interface
and Link Adapter Units used.
Communications Errors
Section 4-2
