Mitsubishi Electric AE-200A Service Handbook page 82

[V Troubleshooting]
[How to check when a LAN communication error occurs in a system connected via a router (how to isolate the cause)]
When LAN communication is not performed properly (pinging is not successful*1) in a system connected using a router, you can
isolate the cause as follows.
*1 Check whether pinging the AE-200/AE-50/EW-50 from a PC is successful when there is a connection via a router in advance.
Step
1 Prepare a PC that is connected to the same network. Use a PC in the
same network with no connection via the router.
2 Ping the AE-200/AE-50/EW-50 or other target equipment from the PC.
Run the following in the command prompt.
ping␣－t␣[IP address of target equipment]
[Example] ping -t 192.168.1.1
⇒ When pinging is successful:
There may be a problem with the gateway setting of the target
equipment or the router settings. Consult with the equipment
administrator.
For the gateway address setting, check "8-2-6. Network settings" in
AE-200/AE-50 Instruction Book.
For the router settings, check the Instruction Book of the router.
⇒ When pinging failed:
There may be a problem with the IP address setting of the target
equipment. Check the setting.
If the problem still cannot be resolved, there is likely to be a problem
with the network of the router. Consult with the system administrator.
[How to check that an IP address is not duplicated]
If it is not possible to check the IP addresses of all equipment, there is the following method using a PC to check with the command prompt.
(Supplement) If all connected equipment in a system in an existing network cannot be checked, you can compare the MAC addresses of
the equipment of only the air conditioning control system to check if an IP address is duplicated.
Step
1 Prepare a PC that is connected to the network.
2 Ping the IP address of the AE-200/AE-50/EW-50 from the PC while
the AE-200/AE-50/EW-50 is disconnected from the LAN.
If there is a response, there is equipment with the same IP address as
the AE-200/AE-50/EW-50. Consult with the network administrator.
Method
Single-byte space (1 character)
Method
78
Supplement
If there is no PC connected to the network,
identify an IP address that it is alright to use
and then connect a PC with that IP address
set.
* For the operating procedure, refer to
[Ping check method] on the previous
page.
Supplement
If there is no PC connected to the network,
identify an IP address that it is alright to use
and then connect a PC with that IP address
set.