Backend appears to closedown before my raster filter sends output

[Paul Newall]

My raster filter works OK with small pages.
But when I print large pages at high resolution, which take longer to RIP (more than 30 seconds), the filter output does not seem to get sent to the (network) printer.
I guess the backend has timed out before I send any data.
Does this sound likely?
How could I confirm that is the problem?
Can I extend the timeout time for the backend?