Troubleshooting

Use this page for first-pass checks when your PLC does not respond as expected. For address-shape mistakes and helper-specific surprises, see GOTCHAS.md.

Connection checks

Symptom	Check
Connection timeout	Confirm the PLC host is 192.168.250.100 or the address you configured.
TCP connection refused	Confirm Computerlink is enabled on your PLC and TCP port 1025 is open.
UDP requests do not return	Confirm you are using the PLC UDP port configured for your target; examples use 1035 for UDP.
Intermittent timeouts	Set Timeout, Retries, and RetryDelay on ToyopucConnectionOptions.

Addressing checks

Symptom	Check
Unknown device area	Confirm the selected PlcProfile supports that family.
Address out of range	Compare the profile in PROFILES.md with the family table in SUPPORTED_REGISTERS.md.
Basic address rejected	Use P1-, P2-, or P3- for basic families such as D, M, X, Y, T, C, L, N, R, and S.
Dword read returns a bit	Use :D for dword access and .D only for bit 13 inside a word.

Write checks

Symptom	Check
A write appears to work but changes the wrong value	Stop and confirm you are using a test address you control.
FR value does not survive power cycle	Stage with WriteFrAsync and then commit with CommitFrAsync.
Relay write or read does not reach the target PLC	Set RelayHops explicitly in ToyopucConnectionOptions.