tgl@g.gp.cs.cmu.edu (Tom Lane) (11/29/90)
I'm running into peculiar behavior of a 7550B (Plus) plotter. I narrowed it down to a small test program that repeatedly reads the "OP" (output scaling points) and then "OS" (output status) responses of the plotter; this is across HPIB. Normally the OS value is 16, which is reasonable (bit 4 indicates input buffer empty). But, about one time in ten, seemingly at random, the OS value is 32, which indicates that an HPGL error has occurred. My program is set up to read the error code (OE) when this happens, and the result is always 0 (no error). What gives? This doesn't happen with 7550A or older plotters. -- tom lane Internet: tgl@cs.cmu.edu UUCP: <your favorite internet/arpanet gateway>!cs.cmu.edu!tgl BITNET: tgl%cs.cmu.edu@cmuccvma CompuServe: >internet:tgl@cs.cmu.edu