Resolving Error Code 192 on AdvancedHMI with Omron NX1P FINS

1. Problem Definition

AdvancedHMI applications running against an Omron NX1P or NX1P2 controller via the OmronEthernetFINSCom1 managed driver (part of MfgControl.AdvancedHMI.Drivers) report Error Code 192 at the COM port level and drop every subscribed tag in the project tree when the controller returns a non-success FINS response for any poll. The visible behavior is a frozen panel with red "PLC communication fault" overlays even though the NX1P is reachable on TCP/UDP, responds to ping, and remains fully accessible to Sysmac Studio.

The error does not indicate a physical disconnection of the Ethernet link. It is a transport-layer fault raised by the .NET driver when one or more FINS responses carry a non-zero response field, and it has been reproduced consistently against controllers that are still fully operational at the application level — most frequently at machine start-up, during hot-swap of NX-ECC EtherCAT couplers, or when a single NX-IO slice drops off the distributed rack.

This reference covers the protocol-level root cause, the Wireshark capture procedure, controller-side mitigation inside Sysmac Studio, and driver-side workarounds until the upstream maintenance release is in place.

2. Symptom Matrix

The contrast between the failing driver layer and the operational Sysmac Studio monitor is the strongest single indicator that the fault is in how the driver interprets a FINS response code — not in the controller.

3. Root Cause: FINS Response 0x0040 Treated as Hard Comms Fault

The AdvancedHMI FINS driver maintains a per-connection state object that increments a fault counter on any non-zero FINS response field. When the counter reaches a configured threshold (one count is sufficient in the affected build), the connection is marked as failed, the COM port stops being polled, and every subscriber attached to that port receives the cached error code.

The numeric value reported to the application — 192 decimal (0xC0) — maps to a vendor-specific error category inside the driver's exception path. Concurrently, Wireshark captures of the same conversation show the controller is returning the FINS response code 0x0040 (decimal 64). Per Omron's FINS specification this response indicates that the requested address, memory area, or variable is not accessible to the requester at the current mode. On an NX1P/NX1P2 with cross-memory protection active, or with a global symbol that has been deleted from the project, this is the expected reply for a transient or invalid read — it is not an indication that the controller is unreachable.

The problem is therefore a policy mismatch: the controller is responding correctly with a FINS-level fault, while the driver treats the same response as a transport-layer failure and locks the port. The latch is held in the driver's in-memory state; a runtime restart is required to clear it unless a workaround re-creates the COM object.

4. FINS Protocol Background for NX1P / NX1P2

Factory Interface Network Service (FINS) is Omron's application-layer protocol that runs over Ethernet on the NX1P-series CPU units. Documented in the Omron SYSMAC CS/CJ/CP1E/CP2E-series Communications Commands Reference Manual (W342) and the NX-series CPU Unit Hardware User's Manual (W525), FINS supports the following transports on an NX1P:

• Port 1 (built-in Ethernet/IP): FINS/UDP on UDP port 9600 and FINS/TCP on TCP port 9600.
• Port 2 (built-in EtherCAT master): reserved for real-time I/O. FINS does not ride EtherCAT; distributed NX-IO slices are not addressable from FINS at all.
• The NX-ECC201 / NX-ECC202 EtherCAT coupler used to attach distributed NX-IO slices is reachable only via EtherCAT process data, not via FINS.

A FINS response carries a two-byte status field. The most-significant byte is the main response code (MR) and the least-significant byte is the sub response code (SR). A successful reply carries 00 00. The byte pattern 0x00 0x40 (MR=00, SR=0x40) is the documented Omron response for "the destination cannot recognize the specified memory area" — common causes being (a) a variable name that no longer exists in the project, (b) a memory address outside the CPU's accessible range, (c) cross-memory protection denying the FINS node's read access, or (d) an optimisation sweep that has eliminated the variable from the publishable symbol table.

For the NX1P2 specifically, only FINS/UDP is universally exposed in many firmware builds; the legacy FINS/TCP path used by CP1H/CJ2 projects is not always present. Drivers written against the older protocol stacks occasionally assume TCP semantics on a UDP socket, which can also surface as the same 192 error if the connection times out under load.

5. Affected Software Versions and Environment

6. Diagnostic Procedure with Wireshark

Reproducing the fault and confirming the FINS response code on the wire is the single highest-value diagnostic step. It distinguishes this driver bug from a genuine physical-layer fault and produces evidence that survives vendor support escalations.

6.1 Capture Setup

1. Install Wireshark 3.x or later on a Windows or Linux workstation that can span or mirror the traffic between the HMI PC and the NX1P. A managed switch with port mirroring is preferred; a passive tap or hub on a 100 Mbps legacy segment is acceptable.
2. Start a capture on the mirrored interface with the filter fins || udp.port == 9600 || tcp.port == 9600. This restricts the capture window to FINS traffic only and avoids filling the buffer with unrelated EtherCAT/IP traffic.
3. From the HMI runtime, force a single tag read (for example, click a button that reads D100 or a named global symbol) so the controller generates a deterministic reply on demand.
4. Save the capture as a .pcapng file alongside a timestamped note of the AdvancedHMI ErrorCode as displayed in the diagnostic window.

6.2 Reading a FINS Reply Frame

The decoded packet for a non-success case resembles the following:

FINS/UDP
  Source port:      9600
  Destination port: 9600
  Length:           14
  ICF:              0x80   (response, command bit cleared)
  RSV:              0x00
  GCT:              0x02
  DNA:              0x00
  DA1:              0x01
  SNA:              0x00
  SA1:              0x01
  SID:              0x42
  Response code:    0x0040 <-- main=0x00, sub=0x40
  Command/data:     0101 8001 ...

If the response code byte is non-zero, capture the entire frame and attach it to any escalation. A response code of 0x00 0x40 indicates an address-area-not-recognized fault, the value most strongly correlated with the AdvancedHMI 192 error.

6.3 Confirming the Driver Path

Temporarily stop the AdvancedHMI runtime, then connect to the same controller with Sysmac Studio using a different PC and a separate FINS/UDP node number. If Sysmac Studio reads the same variable without fault, the controller is healthy and the driver is the source of the alarm.

6.4 Diagnostic Flowchart

7. PLC-Side Mitigation in Sysmac Studio

Eliminate every legitimate FINS fault at source. The driver's over-reaction only happens when the controller returns a non-zero response, so removing those responses reduces the probability of the latch.

1. Clean the global symbol table. Open the project, view the global variables, and delete or rename any symbol that is no longer used. Symbols that are not mapped to any task and not exposed to external access cause the 0x0040 response when a FINS name query or symbolic read is issued.
2. Verify cross-memory protection. On NX1P2 with project security enabled, confirm the FINS UDP connection's node number is included in the "Read Protection for External Access" / "Write Protection for External Access" exclusion list. Cross-memory protection is enforced at run time and silently blocks reads from any FINS node that is not whitelisted.
3. Rebuild and re-download. A full project rebuild with download ("Transfer to Controller → Transfer all") often removes orphaned addresses. After download, cycle the controller from PROGRAM to RUN mode once.
4. Resolve every EtherCAT minor fault. The NX1P raises a controller-level minor fault whenever any distributed slice loses communication. Use the EtherCAT configuration editor's slave diagnostics tab, identify the dropped slave by node address, and either restore the physical connection or disable the slave in the configuration (and recompile).
5. Reserve a static node number. Avoid DHCP-leased node numbers on the FINS port. Set a fixed FINS node number (for example, 10) in the controller's built-in Ethernet settings, and configure the AdvancedHMI driver with the same node number in the PLCAddress field of the driver property sheet.
6. Confirm FINS routing table. For multi-layer setups, verify the controller's routing table includes a local-network entry that the HMI PC's IP belongs to; otherwise FINS queries can take the slow path and time out.

8. Driver-Side and Application-Side Workarounds

Where the controller cannot be retuned (for example, on a shipped-instrumentation retrofit that is under warranty), wrap the AdvancedHMI COM driver with retry logic and tag-availability checks in the host application.

8.1 Driver Configuration Tuning

• Slow the poll interval. Increase the per-tag poll to longer than 200 ms. The driver retries faster than the controller can queue replies during a transient slice loss, so a slightly longer dwell avoids the cascade.
• Pin the FINS UDP port. If the driver property sheet exposes a local port selector, pin it to a fixed value above 1024 (for example, 9601). The same node-numbered port is reused after each reconnect, which avoids socket-exhaustion under repeated fault cycles.
• Enable force-reinitialise on error. Where the driver exposes a "force re-initialise on error" toggle, enable it. This forces the driver to drop its internal fault latch when a non-zero response is seen, instead of holding the port in error until the user restarts the runtime.
• Avoid overlapping reads with writes. When other tools (Sysmac Studio, CX-Designer) are consuming tags on the same port, the controller can serialize requests and one tool's request for a deleted variable will trip the other's driver latch. Run only one FINS client during commissioning.

8.2 Application-Layer Retry in C#

// Wrap every read against the affected PLC driver.
// The exception path recreates the COM object so the
// in-memory fault latch is cleared on every fault cycle.
private static bool TryRead(OmronEthernetFINSCom1 driver,
                             string address,
                             out object value,
                             int timeoutMs = 1500)
{
    var sw = System.Diagnostics.Stopwatch.StartNew();
    while (sw.ElapsedMilliseconds < timeoutMs)
    {
        try
        {
            driver.Read(address);
            if (driver.ErrorCode == 0 &&
                string.IsNullOrEmpty(driver.ErrorMessage))
            {
                value = driver.LastValue;
                return true;
            }
        }
        catch (DriverException)
        {
            driver.Dispose();
            driver = new OmronEthernetFINSCom1();
            driver.PLCAddress = "10.10.10.20";
            driver.NodeNumber   = 10;
        }
        System.Threading.Thread.Sleep(100);
    }
    value = null;
    return false;
}

This pattern is a viable workaround until the driver is patched upstream. On a slow HMI, wrap the call in a low-priority thread so the UI does not block on the recycle loop.

8.3 Diagnostic Block for Sysmac Studio

The following structured-text block, placed in a periodic task, lets you verify which FINS sub-code the controller most recently returned without leaving Sysmac Studio:

// ST (Structured Text) — Sysmac Studio periodic task body
IF _Port1_FINS_Status = _eFINS_RESPONSE_ERROR THEN
    CASE _Port1_FINS_LastSubCode OF
        16#0040: // Address area not recognized
            TriggerAlarm('FINS Address Error');
        16#0101: // Local node not in network
            TriggerAlarm('FINS Local Node Offline');
        16#0202: // Remote node not in network
            TriggerAlarm('FINS Remote Node Offline');
        ELSE
            TriggerAlarm('FINS Generic Error');
    END_CASE;
END_IF;

Logging the actual sub-code confirms that the request has an addressing problem on the controller side, not the driver side, and rules out the driver bug for that specific tag.

8.4 Switching to OPC UA as an Architectural Alternative

NX1P/NX1P2 controllers support OPC UA as an access method independent of FINS, with a request/reply model that is not subject to this FINS-specific driver bug. Bridging the HMI through an OPC UA server (for example, the Omron OPC UA Server plug-in, or a third-party gateway) allows legacy AdvancedHMI projects to read NX1P tags without re-hosting the HMI. The migration cost is medium — drag the tag list through the OPC UA client and rebind in the HMI — but the residual risk after migration is the lowest of all the options in the next section.

9. Resolution Matrix

10. Verification

After applying any of the above, complete the following checks to confirm the fault is gone:

1. Disconnect a non-critical NX-IO slice (for example, a spare NX-IDO module) while the HMI is running. The driver must log the fault and continue polling the remaining tags without freezing the screen.
2. Reconnect the slice and confirm the controller exits its minor-fault state on the next task scan; the slave's status word on the EtherCAT diagnostics page should return to OP.
3. Re-run the Wireshark capture with the same filter as Section 6 and verify FINS response codes are 00 00 for the tags the HMI is consuming.
4. From the AdvancedHMI diagnostic window, confirm the COM object's ErrorCode returns to 0 within one poll cycle of the underlying fault clearing.
5. Observe the controller's FINS port diagnostic counters in Sysmac Studio; no further 0x0040 sub-codes should be logged after the global symbol cleanup.
6. Run an automated soak test that toggles a non-critical slice's connection state every 30 minutes for 24 hours; verify the HMI never freezes and the ErrorCode always recovers.

If the driver still latches after all of the above, the most likely remaining cause is an out-of-date driver assembly being pulled in by the host project's reference list. Confirm the file version of MfgControl.AdvancedHMI.Drivers.dll on the deployed machine matches the version on the build machine; mismatches frequently reproduce this exact symptom on otherwise-fixed HMI installations. Verify with Sysinternals Process Explorer — load the host .exe, inspect loaded modules — or run a PowerShell one-liner such as (Get-Item 'C:\Program Files\MyHMI\MfgControl.AdvancedHMI.Drivers.dll').VersionInfo.FileVersion.

11. Document References

• Omron NX-series Controllers — Product Family Page
• Omron Industrial Automation Global Portal
• Wireshark FINS Protocol Dissector Reference
• Omron Industrial Automation Knowledge Base

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