Which COM port should I select in MCRSync?

Symptoms

MCRSync does not communicate with the card, or the correct COM port is unclear.

Why it is unclear

Windows assigns COM port numbers based on the order devices are detected and installed. If you move hardware, reinstall drivers, or connect other serial devices, the COM number can change. This is why the correct selection may not be obvious.

How to identify the correct COM port

1. Open Windows Device Manager and expand Ports (COM & LPT).
2. Look for the entry associated with the Masterclock PCIe card or its serial interface. Note the COM number.
3. If you are unsure which entry is correct, unplug or disable other serial devices temporarily, then refresh Device Manager and note what changes.

Confirm in MCRSync

1. In MCRSync Config, select the COM port you identified.
2. Open MCRSync Monitor and verify that status values update and the card reports expected information.
3. If there is no response, try the next likely COM port from Device Manager.

Tips

• Use a consistent slot and avoid frequently moving the card to reduce COM reassignment.
• If COM ports appear to change after updates, re-check Device Manager and update drivers as needed.

Related articles

• What do S and T values mean in MCRSync Monitor?
• PCIe card installed but not functioning as expected