Symptoms
When connecting to a Presentation Server 4.0 server farm with Program Neighborhood 9.15 using COM port mappings, the following errors occur:
With the parameter CommPollSize=On:
When the COM port is used within the ICA session, wfica32.exe uses 100 percent of the CPU.
With the parameter CommPollSize=Off:
When the COM port is used within the ICA session, the CPU usage goes down to 10 percent, but the COM port device is disconnected.
Resolution
Timer is another variable for CommPollSize.
Timer was introduced to avoid 100 percent CPU usage when using the CommPollSize=On parameter.
In conjunction with this, depending on your specific device in use, you may need to test various values for the CommPollWaitIncTime parameter.
To make these changes, use the following procedure:
1. Edit c:\Program files\Citrix\ICA Client\module.ini under the heading [ClientComm].
2. Edit the two parameters (CommPollSize and CommPollWaitIncTime) as shown below:
[ClientComm]
DriverName = VDCOM30.DDL
DriverNameWin16 = VDCOM30W.DLL
DriverNameWin32 = VDCOM30N.DLL
WindowSize = 1024
CommPollSize = Timer
CommPollWaitMin = 0
CommPollWaitMax = 500
CommPollWaitInc = 1
CommPollWaitIncTime = 100
More Information
CTX106319 – MetaFrame Presentation Server 4.0 Administrator's Guide
CTX384590 – Troubleshooting COM Port Redirection Issues
