Problem Definition
This case study provides troubleshooting suggestions for COM Port mapping problems on UNIX ICA Client devices.
Environment
Server-Side Configuration:
• MetaFrame 1.8
• MetaFrame XP
• MetaFrame Presentation Server 3.0
• Citrix Presentation Server 4.0
Client-Side Configuration:
• UNIX ICA Clients
Troubleshooting Methodology
1. If using Sunray or thin terminal UNIX devices, first verify that the COM port mapping works when attached directly to the Sunray server itself: To perform this simply connect the device to the Sunray server and test using the ICA Client. Verify if you are able to map the COM ports on the Sunray server using an ICA connection.
2. Locate the [ClientComm] section in the Sparc client's module.ini. Add/Change the CommPollSize key value from off to on and also add/change the CommWakeOnInput key with the value on. Exit the client and then test the scenario connecting to the server with the new module.ini settings: These settings configure the client to be a bit more responsive to incoming serial port data and information.
3. If the Baud rate on the COM port device is adjustable, (presumably from their custom application) try lowering it. The Baud rate, is a measure of how fast data is moving between instruments that use serial communication.
Typical Baud rates include:
300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, or 57600
4. Even after adjusting the Baud rate on the device there is a possibility that the device is getting more data coming from the computer/ICA Client than it can process (basically consuming the device's buffer storage space). To counteract this problem, enable software or hardware flow control (if the custom application that uses the serial device supports this feature and can be configured as such verifiable via the application vendor or hardware manufacturer). Flow control is the process of pacing data transmission so that the receiver has a chance to process all incoming characters before the transmitter sends additional data. Flow control (also known as pacing) is a way to prevent a flow of bytes from overrunning the device. Overrunning is a scenario whereby a device doesn't have the capacity to process the incoming data quickly enough, which results in lost bytes and/or other serious errors: Flow control halts the flow of bytes until the device is ready to accept more data and works by sending its signal to halt the flow in a direction opposite to the flow of bytes it wants to stop.
5. The following information can also be used to obtain in-depth information in regards to COM port communication problems:
If running an application in a Terminal Services Server, Serial Port Monitors can be used to diagnose, analyze and verify if the application or device is actually sending and receiving the correct information. Common Serial Monitor applications/utilities can be found at www.sysinternals.com. Also available from www.softpedia.com is a tool called simpleTerm which is an RS232 Monitor/Analyzer: SimpleTerm is an advanced serial port test, simulation, and data analysis tool which can be used to log, view, and analyze RS232 communication: This information can then be supplied to Citrix's Escalation and Engineering Department for further analysis.
The Serial Monitor can be used to monitor the flow of data between serial devices and Windows applications in addition to Debugging COM port connections (see below):
