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Applications / Re: Can I use a usb port as a com-port?
« on: March 22, 2017, 06:37:47 pm »
Hallo Lars,
I must say that I am not convinced that your current USBCOM.SYS cannot be used to drive the relays. It is my understanding that Roberto did not use an external power supply at that time. May be we did not try hard enough with slight modifications of my original script to get it working. We jumped to using the USBCALLS - REXX/2 External Functions.
I agree that USBCOM.SYS is the proper place to support serial communications thru the various pl2303 chip versions. Browsing the internet I learned that the very same vendor specific code is used again and again when someone supports the pl2303 in his code. It was originally derived from snooping what happens under windows. The actual working is unknown. I think that the VendorGetMagic calls are redundant i.e. the information obtained is not used. May be windows used it to probe what pl2303 version thy are dealing with.
In practice it is impossible to reliably fix USBCOM.SYS without the hardware at hand. Moreover it could break existing support for the various pl2302 hardware that people are currently using.
Wim
Hallo Wim,
do you think that we will manage to fix USBCOM.SYS so that it will do what you now did with the help of USBCALLS.DLL ?
Obviously, USBCOM.SYS is the proper place to put this, in particular the vendor specific Setup. I remember that David Azariewicz added some specific code which I think he also took from file "pl2303.c" but maybe the vendor specific Setup is not working correctly yet.
Lars
I must say that I am not convinced that your current USBCOM.SYS cannot be used to drive the relays. It is my understanding that Roberto did not use an external power supply at that time. May be we did not try hard enough with slight modifications of my original script to get it working. We jumped to using the USBCALLS - REXX/2 External Functions.
I agree that USBCOM.SYS is the proper place to support serial communications thru the various pl2303 chip versions. Browsing the internet I learned that the very same vendor specific code is used again and again when someone supports the pl2303 in his code. It was originally derived from snooping what happens under windows. The actual working is unknown. I think that the VendorGetMagic calls are redundant i.e. the information obtained is not used. May be windows used it to probe what pl2303 version thy are dealing with.
In practice it is impossible to reliably fix USBCOM.SYS without the hardware at hand. Moreover it could break existing support for the various pl2302 hardware that people are currently using.
Wim