An Ewon device running firmware EW_11_2s1 can reach the target S7-300 by ping, but its configured S7-300 I/O Server reads no tags. The reported I/O Server status-register value is 2, interpreted in the available evidence as “connection not OK.” Treat this as a connection-layer fault until the device establishes an I/O Server session.
Separate Ping Reachability from Tag Communication
A successful ping confirms that an IP path exists between the Ewon device and the ping target. It does not prove that the S7-300 I/O Server can open the socket or exchange tag data. Diagnose the failed I/O Server connection independently of remote PLC reachability.
Confirmed Conditions and Open Questions
| Item | Evidence | Engineering decision |
|---|---|---|
| PLC | S7-300 | Keep the investigation within the configured S7-300 I/O Server path. |
| Ewon firmware | EW_11_2s1 |
Use this exact revision when checking device records or escalating the case. |
| IP reachability | Target responds to ping | Do not treat ping as proof of socket or tag access. |
| I/O Server status |
2, reported as connection not OK |
Resolve the connection failure before troubleshooting tag values. |
| Unread tags | No values returned | Expected outcome cannot be verified until the connection becomes valid. |
| Missing evidence | No endpoint details, tag definitions, logs, or socket diagnostics supplied | Do not assume a port, address, rack/slot setting, or root cause. |
Troubleshooting Procedure
- Record the active Ewon firmware, S7-300 I/O Server configuration, status-register value, and the exact PLC target that responds to ping.
- Confirm that the I/O Server is configured for that same target. Recheck every entered connection field against the actual PLC configuration without substituting assumed values.
- Capture the Ewon diagnostic or event information produced during one connection attempt. Look for the exact socket or connection failure text; the status value alone does not identify whether the cause is addressing, transport access, or configuration.
- After correcting any verified mismatch, retry the connection and confirm that the status no longer reports
2. Then test one configured tag before validating the complete tag set.
Verification and Escalation Data
Success requires both a valid I/O Server connection state and a readable configured tag; ping alone is insufficient. If the status remains 2, provide the Ewon configuration fields, PLC network settings, one tag definition, and the diagnostic output from the same failed attempt to the appropriate manufacturer support channel. Mask credentials, but retain exact error text and firmware identification.
FAQ
Why can I ping an S7-300 but cannot read tags through Ewon?
Ping confirms IP reachability only. The reported I/O Server status value 2 shows that the tag communication connection is still not OK.
What does S7-300 I/O Server status register value 2 mean?
In the supplied case, value 2 is identified as “connection not OK.” Capture the corresponding diagnostic output because the status value does not establish the underlying cause.
How do I verify the Ewon S7-300 connection after changes?
Retry the connection, verify that the status no longer reports 2, and read one configured tag successfully before testing the full tag set.