Omron E5AR - MANUAL 2 User Manual

Section 10 Troubleshooting
10-8
Troubleshooting
10.6 Inferring causes from conditions
(communication problems)
● Cannot communicate. No response.
Possible causes Solution
Communication
conditions
The communications speed differs from the host
system.
Make sure that the communications speeds are
the same.
The communication conditions are different from
the host system.
Make sure that the communication conditions are
the same.
Connections
The number of parallel connections exceeds the
rating.
Do not exceed the rating.
• For RS-485, a maximum of 31 units can be
connected.
The length of the communication path exceeds the
rating.
Do not exceed the rating.
• For RS-485, the total maximum length is 500 m.
Another unit has the same unit number. Make sure there are no duplicate unit numbers.
Noise is corrupting the communication data. • Separate the communication cable from the
noise source.
• Use shielded communication cable.
• Use an optical interface.
• Have the program resend the command when a
problem is detected in the response.
Incorrect use of communication devices:
• Optical interface
• 232C-485 converter
Verify the method of use in the literature for each
device.
Incorrect installation of RS-485 terminators. Install terminators only on the devices on the ends
of the communication path.
Program
Communication begins as soon as the power of the
E5AR/ER is turned on.
Wait at least 2 seconds before beginning
communication after the power is turned on.
Unstable signals that occur when the E5AR/ER is
turned on or off are read as host system data.
Initialize the host system reception buffer at the
following times:
• Before sending the first command.
• After the power of the E5AR/ER is turned off.
The host system sends a command before
receiving a response from the E5AR/ER.
Ensure that the program always reads the
response after sending a command.
The interval between receiving a response and
sending the next command from the host system is
too short.
Allow an interval of at least 5 ms after receiving a
response before sending a command.
Mistake in host system program. • Correct the program.
• Check the command in the line monitor.
• Try running a sample program.
Settings
The unit number setting is different from the unit
number specified in the command.
Make sure the unit numbers match.

Omron E5AR - MANUAL 2 Specifications

General

Brand	Omron
Model	E5AR - MANUAL 2
Category	Controller
Language	English