Problem: Unable to operate handheld barcode scanners in a Citrix environment
We have an application WPCTEL that communicates to a scanner (Telxon PTC-710)
WPCTEL communicates to the scanner through the MSComm component. When the application is executed on a stand-alone computer, it works great with no problems. When we execute this application through Citrix Terminal Services, the application does not work.
Fault identification steps:
WPCTEL worked on a polling basis where the application keeps on polling the MSComm component. Through investigation we found that the MSComm component gives us, through the communication process, an error 8020: “Error reading comm device”.
We then ignored the error code until we get a valid response. The DSR is holding during this phase. We then implemented a delay function, for the application to wait for a response from the scanner. This seamed to work, but is not reliable. When it was tested on the client side (through modem) it did not work.
WPCTEL was then changed to work on the onComm event. This means the application waits for the event to fire. When the onComm event fire, and you ask for the information in the buffer, the error 8020 is displayed (at random intervals).
The Citrix configuration for Comm port polling was set on False or Off. We then tried it with the polling on, with no success.
We then had a look at other Comm components and tried the GreanLeaf’s component CommX.
The CommX component does not seem to be able to receive all the characters from the scanner.
Regards,
Daniel Schotter (DanielS@trencor.net)
We have an application WPCTEL that communicates to a scanner (Telxon PTC-710)
WPCTEL communicates to the scanner through the MSComm component. When the application is executed on a stand-alone computer, it works great with no problems. When we execute this application through Citrix Terminal Services, the application does not work.
Fault identification steps:
WPCTEL worked on a polling basis where the application keeps on polling the MSComm component. Through investigation we found that the MSComm component gives us, through the communication process, an error 8020: “Error reading comm device”.
We then ignored the error code until we get a valid response. The DSR is holding during this phase. We then implemented a delay function, for the application to wait for a response from the scanner. This seamed to work, but is not reliable. When it was tested on the client side (through modem) it did not work.
WPCTEL was then changed to work on the onComm event. This means the application waits for the event to fire. When the onComm event fire, and you ask for the information in the buffer, the error 8020 is displayed (at random intervals).
The Citrix configuration for Comm port polling was set on False or Off. We then tried it with the polling on, with no success.
We then had a look at other Comm components and tried the GreanLeaf’s component CommX.
The CommX component does not seem to be able to receive all the characters from the scanner.
Regards,
Daniel Schotter (DanielS@trencor.net)
