New Serial Com Behaves Differently?

[MarkhP]

I guess this is the right forum..

We have a Sheet Metal Punch that is programmed from a DOS pc via the pc's com1 serial port. The computer is ancient, running MSDOS 6.22 and is on its last legs. I ghost imaged the drive onto a new P3 Computers drive. It is still running MSDOS (it is the exact image of the old pc), but the communications fail suggesting baud rate or handshaking to be at fault. The DOS Mode command is still set to 4800,n,8,1 as before. Nothing has changed software wise, just the new pc that is housing the hard drive. Can anyone think of what may be different now? Would the newer UART for instance make a difference?. Any suggestions welcomed! Thanks.

 

[edfair]

Shouldn't be a difference with anything but the speed of the machine.
In the dim recesses of the memory I recall some issues with handshaking but that was before the PC pretty much dictated how things were to work.
You might try throwing one of the line indicators between machines to see if there is some difference in voltage levels of the handshaking lines. Or use a VOM.
You might also try slowing the PC down to see if that affects it.

http://www.qaug.com

used to have a slowdown program available.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[mradmin]

I, too, support some older equipment and it has been a chanllenge to make some things work with newer computer hardware. The handshake may be your problem: the newer UART chips don't neccisarily have the same defaults as the old ones. at the normal DOS prompt, issue the "MODE com1" command and see what the setup is for xon/xoff, DSR, etc. These may also need to be set to match your existing device & cabling. good luck

 

[MarkhP]

Thanks for your responses. I will look into trying your suggestions.

 

[oisnds]

I think at this point I would check the CMOS/BIOs to make sure that the com port is active and has the address I think it does. With a newer PC an internal modem or other device could be com1 instead of the visable serial connector.