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From: rpainter@encore.com (Rich Painter)
Newsgroups: comp.dcom.modems
Subject: Microcom QX/V.32 problems
Keywords: Microcom QX/V.32 MNP modem V.32
Message-ID: <126654@infocenter.encore.com>
Date: 30 May 90 20:25:41 GMT
Organization: Encore Computer Corp, Fort Lauderdale, FL
Lines: 67


 I have been experiencing significant problems with the Microcom QX/V.32
 modems for many months.  These problems come in two basic flavors:
 command functions and operational carrier losses.
 
 Operational carrier losses are seen only when the telephone line
 exhibits line disturbances.  These disturbances are typically pops,
 clicks, and stepper chatter which happen intermittently.
 Microcom claims that the unit will tolerate these conditions and
 continue operating, sometimes in a speed-degraded mode.
 
 Microcom has tested my questionable modems and pronounced them healthy
 but the problems still occur.
 
 Below I have summarized my problems.  Does ANYONE else have these or
 related or other Microcom problems?  I have been getting a cold shoulder
 from Microcom...
 
 1.  Connection interruption (+++) in 9600 and 2400/REL causes improper
     response on the serial interface.  The usual new line and OK
     strings do not appear but junk characters do.  This could be a
     temporary parity or speed switch.  The first command issued
     (usually ATH) is executed but junk characters are echoed on the
     serial port.  The normal command echo sequence is restored
     following the first command execution.
 
 2.  A problem similar to the previous occurs when the unit is left in
     the command mode and set for no answer (S0=0).  When the telephone
     rings the modem posts a RING string to the serial port.  Sometimes
     it prints junk characters.
 
 3.  When NO CARRIER appears unexpectedly, the REMOTE modem
     is permanently hung.  It keeps the telephone line off hook, will
     not respond to anything sent to the serial port, and will not reset
     using the reset button.  The unit must be powered off then powered
     on to reset it.
 
 4.  While connected at 9600 baud, the units will stop passing data.
     The test light will flash on then off.  The connection will be
     maintained forever but no data will be transmitted or received
     afterward.  Listening in on the telephone line, one hears a
     constant-amplitude, constant frequency tone produced by the modem.
     The reset button must be pushed to reset this condition and break
     the connection.  Generally, following this condition the remote
     modem is hung as previously described.
 
 5.  The LOCAL unit exhibits strange behavior sensitivity to the
     numbers stored in the directory.  Given a set of eight (8) specific
     entries, the unit hangs following issuance of AT\F command.  The
     modem will reset with the reset button.
 
 6.  Remote digital loopback does not work.  It reports erroneous
     results.
 
 7.  The unit will not connect with some modems at 2400 baud and less
     without forcing speed to 2400 baud or less (AT%Bx).
 

     +-------------------------------------------------------------------+
     |  Richard A. Painter                                               |
     |  Encore Computer Corporation            717-395-{3660,3648}       |
     |  Senior Technical Specialist            painter@encore.com        |
     |  RD 1, Box 655A                         painter@crnlthry.bitnet   |
     |  Warren Center, PA 18851                uunet!gould!painter       |
     |                                                                   |
     |  (formerly Gould Electronics, Computer Systems Division and SEL)  |
     +-------------------------------------------------------------------+