OPOS Troubleshooting Guidelines



This guide helps diagnose common OPOS (OLE for Retail POS) printer problems on Windows. OPOS printing depends on three layers working correctly:

  1. Physical device & Windows driver
  2. OPOS Service Object
  3. OPOS logical device configuration

Most OPOS issues are caused by misconfiguration, driver/service-object mismatch, or port/permission problems rather than the POS application itself.

1. Common Symptoms and Likely Causes

Symptom Likely Cause
Printer not found / “device not claimed” Logical name mismatch or missing OPOS entry
Cannot open device Port already in use, incorrect port, or permissions
Test print fails in OPOS utility Service Object misconfigured or driver issue
Status events not working StatusBack disabled or not supported by the driver
Works in Windows test page but not OPOS OPOS Service Object or OPOS config problem
Configuration.xml error Missing, corrupt, or inaccessible POS for .NET configuration

2. Verify the Physical Layer First (Always)

Before troubleshooting OPOS:

  1. Confirm the printer powers on, feeds paper, and shows no hardware errors.
  2. Confirm printing works outside OPOS:
    • Print a Windows test page , or
    • Print using the manufacturer’s utility .

Note: If the printer does not work at this stage, OPOS will not work.

3. Confirm the Windows Port Configuration

Check how the printer is connected:

  • USB — often appears as a virtual USB port (e.g., USB001).
  • Serial (COMx) — confirm baud rate, parity, and handshake.
  • Ethernet — typically TCP/IP (often port 9100 for ESC/POS printers).

Ensure:

  • The port number/address in OPOS matches the Windows configuration.
  • No other software is holding the port open.

4. Verify OPOS Service Object Installation

Each OPOS printer requires a manufacturer-specific Service Object .

Check:

  • The Service Object DLL exists (e.g., CSJWPOS.dll , OPOS_*.dll ).
  • The Service Object matches the printer model and connection type (USB/Serial/Ethernet).
  • The Service Object is correctly registered (COM registration).

If unsure, reinstall or repair the manufacturer’s OPOS package.

5. Verify OPOS Logical Device Configuration

OPOS printers are accessed by logical device names , not by port names.

Check that:

  • The logical name in your application exactly matches the OPOS configuration.
  • The logical name points to the correct Service Object.
  • Device properties (port, baud rate, IP address) are correct.

If using POS for .NET, configuration is typically stored in: 

              
                C:\ProgramData\Microsoft\Point Of Service\Configuration\Configuration.xml

Common problems include:

  • File missing
  • File corrupted
  • Application has no read access

6. Permissions and Execution Context

OPOS frequently fails due to permissions.

Check:

  • The application runs under the same user context used during OPOS setup.
  • The user has access to the printer port, Service Object DLL, and configuration file.
  • If running as a Windows Service , ensure the service account has the required permissions.

As a diagnostic step, run the application as Administrator once.

7. Use the OPOS Test Utility

Validate the printer using the OPOS test/configuration utility before testing your application.

Use the utility to:

  • Open (Claim) the device
  • Print a test receipt
  • Check status reporting
  • Open the cash drawer (if applicable)

Tip: If it fails in the utility, the problem is not the Fueltorque POS application.

8. Typical Configuration Properties to Verify

Common OPOS printer properties that cause issues include:

  • DeviceName
  • PortNo or IP address
  • BaudRate
  • Parity
  • Handshake
  • ClaimTimeout
  • StatusBackInterval
  • AsyncMode

If in doubt, start with manufacturer defaults and change one setting at a time .

9. Logging and Diagnostics

When troubleshooting:

  • Enable OPOS logging if supported by the Service Object.
  • Check Windows Event Viewer → Windows Logs → Application .
  • Capture the full OPOS error code and message (codes are often more useful than text).

10. Configuration Changes Require Restart

After changing OPOS configuration:

  • Close the POS application.
  • Restart the OPOS utility (if open).
  • In some cases, restart the PC.

Many OPOS Service Objects only read configuration on startup.

11. Known OPOS Limitations

  • OPOS is sensitive to timing and port contention.
  • Some drivers do not fully support status-back or asynchronous printing.
  • USB printers can re-enumerate and change ports.

12. Escalation Checklist

Before escalating an OPOS issue, collect:

  • Printer make and model
  • Connection type (USB / Serial / Ethernet)
  • OPOS Service Object version
  • Logical device name
  • Exact error message and error code
  • Whether it prints from:
    • Windows test page
    • OPOS utility
    • Application

This information dramatically reduces resolution time.

13. Best Practice Recommendations

  • Standardise on one printer model and OPOS driver version where possible.
  • Document the exact configuration values used for each install.
  • Keep a known-good Configuration.xml backup.
  • Avoid mixing multiple OPOS vendor stacks on the same system where possible.