Most new computers do not include RS-232 serial ports, and a USB/serial adapters is the most common way to connect serial devices such as a Pactor modem or a GPS. Most USB/serial adapters are reliable but unfortunately there are enough bad ones out there to cause a lot of problems. Our current favorites are any of the adapters that use the “FTDI” chipset, for example the Sabrent  CB-FTDI or search Amazon for “FTDI RS232”. Many others also work fine, just be sure that drivers are included for whatever version of Windows you are using.

If you are having problems with a serial device connected with a USB/serial adapter, here are some troubleshooting tips.

First, try to enlist the help of whoever you purchased the adapter from. If it was a Comp-USA store or a low-budget local vendor, then you may find this approach unrewarding. File that away for next time, and keep reading…

The first step in troubleshooting any system is to simplify it as much as possible. If you have multiple devices connected, then remove all but one and focus on that. If you are connecting through a USB-hub (multiple USB ports connected to a single USB-connector on the computer) then remove that, and plug your USB/serial adaptor directly into the computer. Be methodical, take notes, and simplify the configuration to the minimum and get that working before adding other devices.

Next, open Airmail’s Options window (Tools menu) and click the connection tab. Select each com-port in turn and note the description. Find your device and make sure that it is selected. The most common problem is having the wrong COM-port number. Also make sure that the baud-rate is set correctly, some USB adaptors do not like 115200 baud but all should be happy with 57600. (PTC-IIusb modems always use 115200 baud, and Airmail’s “Getfax” fax companion will be happier at 115200 if the modem-firmware is current).

If the device is not visible in Airmail’s options window com-port list, then open Windows Device manager: Right-click on “my computer” and select properties, or open Windows control-panel and select “System”. Click the “Hardware” tab and then the “Device Manager” button. Look for yellow question-marks, this would indicate a device whose driver did not load properly. If you find one of these then you need to identify the device, get the appropriate drivers and then right-click on the device and “update drivers”. Next find “Ports”, expand that (click the little “+”) and look for your USB/serial adaptor. If found, note the com-port number. That same com-port number should appear in Airmail’s Option window (remember to re-open the options window after changing devices), if not they it did not install properly.

If still no luck then make sure you have the correct– and latest– drivers for your USB/serial adaptor. Go to the manufacturer’s website, click on “support” or “dowloads” and find the drivers page. Download the driver-files for your device, save then in a “drivers” folder and then go back to device-manager (above) and try updating the drivers.

If still no luck then you may just have a turkey, see the comments above about Keyspan single-port adaptors or Edgeport multiport boxes. Or find a dealer who can supply an adaptor that they will stand behind, and will help you with if things don’t go according to plan.

Also worth noting: Some adapters assign com-port numbers according to the device serial number, so that a given adapter will always be “COM4” for example. Alternately, some devices assign COM-port numbers according to which USB-socket the adapter is plugged into. In this case moving an adapter from one USB socket to another will cause things to stop working. So a good rule of thumb is to always use the same USB socket for each adapter.

Good luck and good sailing!
Jim Corenman