Using the CPR with Lantronix Device Servers and Fax modems
I have a Microsoft Small Business server 2008 virtual machine that is connected to a Lantronix device server. I have two Multitech 5656ZDX faxmodems attached to the device server. When trying to use the Microsoft Fax service, the modems will dial, connect, but sometimes send a blank page or a partial page. Other times the modems will not dial. I don't know if there is something that is setup wrong or something that is causing a miscommunication between the Virtual Machine and the modems. Any suggestions?
Note: Lantronix Tech Support over all does not support running the CPR program with Virutal Machines or VM ware.
One customer resolved this problem by disabling the "Buffer Writes" setting in the CPR Manager software. While this is not guaranteed to work, it is worth a try.
"Buffer Writes" is a check box on the CPR configuration page.
See PDF page 10 of http://www.lantronix.com/pdf/Com-Port-Redirector_QS.pdf for an illustration of what the virtual Com port configuration page in the CPR looks like.
Background:
If your fax application is designed to communicate with a locally connected modem (i.e. one plugged directly into a Com port on the PC the app is running on) then it is very unlikely that it will work via a CPR connection to a modem connected to a Lantronix device server.
Faxing across a network using a general purpose device server is a complex issue, involving many of variables outside of Lantronix' control. Some combinations of operating system, driver, network environment and fax modem appear to work at least some of the time, while others do not work at all.
Most Fax applications and drivers have strict timing requirements that assume that the fax modem will be directly connected to the host. Adding a network connection between the host and the fax modem will add latency (travel time) to the communication between the host and the fax modem, which may cause the fax application, driver and/or fax modem to time out and abort the fax.
In general, the only way to resolve this type of issue is to contact the manufacturer of the Fax Modem and/or the developer of the Fax Application and request a modification to the driver, application and/or modem that will allow them to work well with a high latency connection.
Another option is to do a web search for "network fax server" to find a list of vendors that sell servers that are optimized for faxing over a network. Currently Lantronix does not offer a specialized network fax server.
[Originally Published On: 04/14/2011 05:07 PM]