Is there a way to test a USB to Serial Cable with only multimeter?

[Lord Banshee]

OK i just got into my MicroProcessor Class here at my college and we are using a board with a Freescale 68HC12 but this board is the last of its design this semester and it only have a serial port to program the 68HC12.

My Problem is my IBM T42 does not have a serial port so i went to circuit city (min away from house) and got a pda USB to Serial Cable.

Well i am wondering if there is a way to test the cable to make sure it works without connecting it to my board. If it does something stupied and F'ths up my board it would be bad as there is no more of this old board left and mass shipments of the newboard has not come in and might not for a month or two, so i can't take too many chances.

During construction of the board it tells me to connect it then to make sure the RS232 chip works and get the correct voltage, that seemed to work but this didn't envole the MicroController at all.

So i am wonder is there a way to either use a custom program or HyperTerminal (this is the prog we will be useing to program our board) to maybe check pin of the of the serial port to make sure the correct signals are going through..


OR am i being too paranoid(sp?) and it should work.

Thanks,
Chris

 

[Bassyhead]

Perhaps you can connect the serial port end to a computer that does have a serial port and run HyperTerminal on both machines.

 

[Lord Banshee]

lol

thats simple idea and a great one... doh!

Thanks,
Chris

 

[Peter]

You need a so called "null modem" cable for that (essentially a crossover cable).

With one of those, you can even connect the USB-serial dongle to a legacy COM port on the same machine, open two instances of HyperTerminal, type in one window and see stuff appear in the other.

 

[wwswimming]

how about putting 5 volt zeners and some current limiting resistors on each line, to limit the voltage
and the inrush current, when you attach the cable.