Maxi MWHE20 - Page 60

TROUBLE SHOOTING
7-18
16. “Er8” RS485 communications error
Problem a communications error occurred during RS485 communications.
Possible Causes
What to Check and Suggested Measures
1. Host controllers (e.g.
PLCs and personal
computers) did not
operate due to
incorrect settings
and/or defective
software/hardware.
Check the controllers.
→ Remove the cause of the controller error.
2. Relay converters (e.g.
RS232C/RS485
converter) did not
operate due to
incorrect connections
and settings, and
defective hardware.
Check the converter (e.g. check for poor contact).
→ Change the various converter settings, reconnect the wires, or
replace hardware (such as recommended devices) as appropriate.
3. Broken
communications cable
or poor contact.
Check continuity of the cable, contacts and connections.
→ Replace the cable.
4. Even though no
response error
detection time (y08)
has been set,
communications did
not occur cyclically.
Check the host controllers.
→ Change the settings of host controller software, or make the no
response error detection time invalid (y08=0).
5. A high intensity noise
was given to the
inverter.
Check if appropriate noise control measures have been implemented
(e.g. correct grounding and routing of control and main circuit wires).
→ Improve noise control.
→ Improve measures against noise from host controllers.
→ Replace the relay converter with a recommended insulated
converter.
6. Conditions for
communications differ
between the inverter
and host controllers.
Compare the settings of the y codes (y01to y10) with those of the host
controllers.
→ Correct any settings which differ.
7. The RS485
communications card
malfunctioned.
→ Replace the card.