Parallel Port Tester

Hopefully I can attach pictures



I despair

There is a single chip, CH351Q

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Great, Tommy and thanks very much and you have saved me a lot of anxiety and I can stop going round in circles. Will now look for a card.
As a slight change in subject when I did the latency test from the hard drive it was horrendous, 30,000,000 +. I am now running on a USB flash drive and it appears ok although mouse can be a bit erratic. The drive is USB 3 and will I benefit from going to USB 3.1(I think)?

Yes
1 full-height PCI 2.3 slot•2 full-height PCIe x1 slots•1 full-height PCIe x16

Hi all,
I'm building a new machine and it seams that I cant get the parallel port working correctly.
I have 3 pins that don't perform at all.
The BOB I've built my self and running it stand alone it works.
The pins not working is PIN  14, 15 and 16 (2 outputs and 1 input) 
In the computer with the latest LinuxCNC installed there are 2 parallel ports the one on the mainboard and a PCI parallel card.
Both behave in the same way.
Between the BOB and parallel port I have a 5 meter cable.

Does anyone have a clue to why it's not working?

BR 
Johan

5 meters of cable is a long run for parallel port operation. It is possible this could be part of your problem. Have you double checked that your cable wiring is complete and separate for all pins (no pins sharing wires.)

Is there a problem with your breakout board design? Could you describe how it's constructed? What do you mean by "stand alone it works"? How are you testing it "stand alone"?

Parallel ports do a much better job of sinking current than sourcing it. You should take advantage of that when designing your breakout board, so that the BOB and not the parallel port is the source of the signal currents. This adds some complexity since two separate current sources will need to be supplied to the BOB if isolation is desired.