SYSMGR@IPG.PH.KCL.AC.UK (08/22/87)
We have a local communications system connecting terminals to our VAXes;
the interface is down RS232 wires with modem control. Until recently it
was working perfectly. Now a fault condition has devloped on two out of
eight ports on the comms. box. We know it was a fault, as someone was
actually using the line when it 'failed'.
The bizarre thing is the nature of the fault. When DCL prompts for input,
the prompt text and whatever one types in response do not echo on one's
terminal. <CR><LF> does echo in response to a <CR>, however.
In all other contexts (VMS utilities, editors, user programs,
logging in, even DCL continuation lines) everything works perfectly.
The text which is not echoed is received by the VAX and acted on correctly.
The other peculiarity is that command line recall, both with cursor keys
and with RECALL <n> does not recall anything. (RECALL/ALL does work).
The fault is definitely associated with the comms. box line and not with a VAX
port. I have connected the faulty lines both to several DHV11 ports on a uVAX
and to TXA1 on a DMF32 on our 11/780; identical problem in all cases. I have
also established that the modem signals supplied on a good line and a bad one
are identical (although I do not have the equipment to monitor for transient
pulses).
I would be extremely grateful if anyone could suggest what might be going
on! In particular, if any VMS wizards know anything special about DCL's
terminal QIOs compared with any other terminal IOs, could they please
let me know. I have spent most of today verifying this fault and establishing
that I am not hallucinating!
Please reply to me, not the net. If I ever get to the bottom if this problem
I will let you know, although I am beginning to despair of that!
Nigel Arnot (Dept. Physics, Kings college, Univ. of London; U.K)
Bitnet/NetNorth/Earn: sysmgr@ipg.ph.kcl.ac.uk (or) sysmgr%kcl.ph.vaxa@ac.uk
Arpa : sysmgr%ipg.ph.kcl.ac.uk@ucl-cs.arpa