Com port loopback test

[Ramya]

I find my serial ports working perfect during stress test in Linux.

But I am having issues in testing serial ports in WinXPE.
When I have DTR/DSR & RTS/CTS signal test phase enabled, OS crashes and reboots. When that is disabled, there are no errors/resets.

My Questions:
1. Why does WinXPE/Win7 not boot when loopback serial plugs are plugged in ports?
2. Why system resets while burnintest is running in WinXP?
3. DTR/DSR & RTS/CTS signal test phase enabled - what does this mean? What tests are done in this case? How is it validating my ports?

Please answer my queries. Thanks in advance.

Ramya

[Ian (PassMark)]

1. Why does WinXPE/Win7 not boot when loopback serial plugs are plugged in ports?

Sounds like a hardware problem. To rule out the loopback plug, I would try a different loopback plug and if you made it yourself I would re-check the wiring.

2. Why system resets while burnintest is running in WinXP?

Sounds like a hardware problem, or Windows XP embedded is missing some required system compoents for serial ports.

3. DTR/DSR & RTS/CTS signal test phase enabled - what does this mean? What tests are done in this case? How is it validating my ports?

In this phase of the test these lines are toggled in software and the new line status checked.

[Ramya]

In Passmark loopback plugs, DCD was linked to DSR and DTR. When ever BIT tests DSR and DTR, their signals go low and high. As DCD is linked to DSR/DTR signals, they go through signal changes and cause hardware interrupt & resets in Windows. That is why even during boot up there is some issue.

So if I want to run DSR/DTR test phase, DCD must not be linked to DSR or DTR. In that case, I can not use Passmark Serial loopback plugs? Could you please confirm whether this is a known issue. Otherwise I need to what I am missing.

Please help!!

[David (PassMark)]

We have selling COM port loopback plugs for +10 years. This is not a known issue.

Hardware interrupts are a normal part of a computers operation. A computer could not function without them. If a hardware interrupt is really causing a hardware reset, then you either have a hardware problem, or a device driver problem.