Psion Teklogix Vehicle-Mount Computer 8590 - Manual (Page 132)

Chapter 7: Serial Ports
Tips & Tricks
106 8580/8590 Vehicle-Mount Computer User Manual
1. Open the Start menu and navigate to Settings>Control Panel>Acces-
sibility.
2. Choose the General tab.
3. Choose Support accessibility options.
4. Click Settings.
5. Configure the desired COM port and BAUD rate.
6. Confirm the change with OK.
7. Click OK again for the changes to take effect.
Important: Keep in mind that you must configure the scanner correctly to
RS-232 and the above set BAUD rate, following the scanner man-
ufacturer's guidelines. Otherwise the software wedge will not
function properly.
7.1.6 Tips & Tricks
Note that according to the EIA-232-E specification, the maximum cable length is 15
m at 19,200 bps.
Malfunctions in the RS-232 connections are frequently caused by ground loops. If
both end devices establish a ground connection via RS-232 but do not share the
same ground potential in their power supply circuits, then compensation currents
may result. This is particularly noticeable with long cables.
These compensation currents, which are also present at the ground point of the
RS-232 connection, may significantly degrade signal quality and effectively stop the
data flow. In challenging environments, electrically-isolated connections (via
external converters) are strongly recommended.