How to use Portmon to Monitor Traffic in Serial Networks
Issue
Serial communications are not functioning on a Modbus daisy chain.
Product Line
Serial Devices
Environment
Windows OS
Portmon 3.x
Resolution
PortMon is a free application that monitors and displays all serial and parallel port activity on the local computer or a remote computer. It intercepts I/O control commands at the driver level and shows detailed information about parameters and data being sent or received.
To monitor traffic in a Modbus daisy chain, the PC running PortMon must be part of the communication (e.g., as a master or slave). PortMon cannot sniff traffic passively on the wire; it only logs what the OS sends/receives through its ports.
How to Run PortMon
-
How to Run PortMon
- Run
PORTMON.EXE. - Go to Computer > Connect (choose local or remote).
- Under Capture, ensure Capture Events is checked.
- Under Capture > Ports, select the port to monitor.
- Events for the selected port will appear in the PortMon window.
- When done, you can Save the log file for review.
- Run
Where to Download:
Portmon can be found on the Windows website by searching Portmon or by following this link: https://learn.microsoft.com/en-us/sysinternals/downloads/portmon.