Equisys technical notes

Technical guidance, explanations and fixes for our products

PRB: Communication failure connecting to second USB modem



ID: ZTN1608

This Zetafax technical note applies to:

  • Zetafax 2007 and earlier
  • USB modems


When using two USB modems with Zetafax, one modem fails.  The following error message is displayed in the Zetafax Server Monitor:

FCLASS1 - Communication failure connecting to modem


The Zetafax device controllers communicate directly with the COM port assigned to the modem. When the port is changed or shared, Zetafax can no longer communicate the modem.


Use two serial COM port modems if possible, if not, use one USB modem and one serial COM port modem.  This will ensure that no conflict occurs between the modems.


This has been identified by Equisys as a problem with the software versions given above.


ZTN1000 - PRB: Modem trouble shooting guide for Zetafax .

Last updated: 9th July 2007 (IN/GC)

Keywords: dialling dialing properties country code TelNumEdit

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