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Manufacturer: Multi-Tech Systems
Model: MT2834ZDX
Model: MT2834ZDXF (version for French market)
Model: MT2834ZDXG (version for German market)
Model: MT2834ZDXK (version for UK market)
Last Updated: Date: 1997/10/15 04:02:00 $


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October, 1997

This modem is recommended for use with HylaFAX.

• It has been mentioned, however, that the AT command &D3 is broken. The workround is to use &C4 in place of &C1.

Hang On Disconnect
• Newer models (e.g. firmware revs 0316D) will occasionally hang when the line drops due to poor line conditions. When this happens, one can observe the TR lamp turning on and off as HylaFAX attempts to reset the modem. However the modem will not respond to any commands it is issued.
  Multitech support recommends using AT&C4, which can be placed in the non- volatile setup, or as the ModemSetupDCDCnd string.

Glenn Burkhardt, with help from Multitech support, passed on the following advice to improve the ZDX 2834's ability to receive faxes. .
• The receive threshold in negative decibels is determined by the S38 register. Its factory default value is 43, changing it to 35 makes it possible to receive faxes from our AT&T 351D fax machine (and probably many others)
• The command ATS38=35 will change the value of the S38 register. To prevent the factory default value from being loaded should a AT&F command be issued, the command AT&F9 is needed.
• The following, one-time, out of the box, initialization for the modem is therefore recommended :

                 AT&F
                 ATS38=35
                 AT&F9
                 AT&W0
       

• The explanation they had was that when the carrier was dropped as part of the normal facisimile handshaking, noise on the line was above the receive threshold level, making the modem think that the carrier had not been dropped. Eventually, the T2 timer expired, and the modem reported +FHNG:73 (T.30 T2 timeout, expected page not received (code 73)). Increasing the modem's receive threshold to -35db keeps the noise level below the carrier, at least for my fax machine and phone lines.

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