internal loopback mode via TIOCM_LOOP

USB Devices
1

I’m trying to get a Acceleport XP into internal loop back mode so that I can test the card without any external hardware connected. TIOCM_LOOP does not seem to be doing it. It doesn’t seem to be doing it for the normal serial ports on the pc either. Is there something other than

#define TIOCM_LOOP 0x8000

ioctl(Q->DevSpec1, TIOCMGET, &tty->modem);
tty->modem |= TIOCM_LOOP;
ioctl(Q->DevSpec1, TIOCMSET, &tty->modem);

required to get the card into this mode. I’m running Linux on an x86 platform.

Thanks
Mark

2

Hi Mark,

(I believe I have responded to your questions before,
so forgive me if I repeat myself)

The Acceleport Xp board is an intelligent board, which has firmware running on it to drive the product.

The firmware does not expose a loopback method to the driver that can be done WITHOUT a loopback plug.

The ioctl you are trying to do below is something you might do with a non-intelligent (dumb) board, which exposes the UART registers directly to you.

From all your questions so far, you might be working on a product that might not best suit your needs.
You probably should look at a non-intelligent serial board, say, something like our Digi Neo products.

Scottk

3

Thanks again for the info. I understand this is an intelligent board. That is no reason for it not to have an internal loopback method. Maybe it’s not that intelligent after all? This product does appear to suit the needs of my application. The particular piece of the application the digi xp is being used for is to emulate an old async comm controller. It functions quite well and Linux support is good. I’m just trying to get the emulation as close as I possibly can. Maybe another card would have been a “wiser” choice from the get go but this is the card I have to use.

Thanks again
Mark