[comp.dcom.modems] PP MNP modem requires careful parity management and new proms

david@wubios.wustl.edu (David J. Camp) (09/29/89)

This is to reveal the successful configuration of the Practical
Peripherals MNP modems mentioned in two previous notes.  Finally I
called the Technical Support at PP, and with a small adjustment in the
configuration, I was able to get the modem to work properly at no
parity.  The problem is a bug in the proms in that particular model, and
PP has promised to send me an upgrade in the mail.  They said I was the
first customer they were able to promise this to.  The temporary
workaround was to set AT&D2 instead of AT&D3.  The problem is there is a
bug in which the stored value for the parity is invalid.  Even when you
use AT&W and AT&V and the modem says it has stored 8N, it is really
storing 7E.  The current value in use may actually be 8N, but if the
modem power is cycled or the ATZ command is issued, or DTR drops with
AT&D3 asserted, then the hidden value of 7E will be restored to the
current registers.  Now that I am using AT&D2, and explicitly setting
the parity to none after power-on, my modem is working properly in
reliability and compression mode with no parity.  -David-

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