Lost Comm Res vs Lost Connection

[znelbok]

What is the difference between Lost Comm Res and Lost connection?

Both seems to mean that the driver is offline (or has gone off-line) to me but I dont actually know what is triiggering the count on either.

I have a projector that has 83650 Lost Comm Res and 0 Lost Connection. Its using the GC100 serial port.

Because its a PDL driver, there is no logging to indicate what has gone wrong (bad reply or something else) so I have to rely on these two values to try and work out what is going on.

Mick

[Dean Roddey]

In some cases there's not a lot of difference, it depends on how careful a driver is to try to figure out the difference between the device just not responding and the actual communications line being lost.

In an IP driver it's quite possible to lose the communications (the other side shut down the socket connection for instance), but it's also possible that you just fail to get an expected response or something or fail to get a response, but you can check to see if the socket is still connected.

So lost connection means that for some reason the driver didn't understand what is happening, so it recycled back to trying to connect and get online. But it didn't recycle all the way back to dropping the comm resource (serial port or socket.) Lost comm res means that it cycled all the way back, closing teh comm resource, then re-opening it and trying connection.

Traditionally it's unlikely that you will ever actually lose a serial port comm resource, but that has become less the case when serial ports are actually being done over some other medium, as apposed to via onboard hardware.

Since it's really hard to tell the difference on serial ports, since they not like sockets where you can check the connection, they will typically just completely recycle and start over, just to be sure. So in that case you will see lost com res going up, but not lost connection. Where it's possible, drivers should be smarter and try to only cycle the connection not the comm resource, but particularly with something like the PDL driver, which is very generic, that's difficult. So it just assumes that paranoia is the best option and goes back to ground zero and starts over.

So basically it got some unknown reply or failed to get a reply and so forth. If you put it into verbose mode it should give some information about what's ailing it, right?