RS232 - How can I know which RS-232 data lines are active
The RS-232 Mini Tester is an efficient device to connect in series with any RS-232 interface for testing a serial (RS-232) link. An example of how an RS-232 mini tester looks like is shown in figure-1 below.
Figure-1: RS-232 Mini Tester
The RS-232 Mini Tester is installed between a host PC and an intended equipment in order to test the serial link for any failures. As can be observed in figure-1, the mini tester has 7 bi-colour (red and green) LED's (Light Emitting Diodes) which indicate the logic states for respective data lines. The colour of the LED indicates Negative or Positive voltage, red meaning negative and green meaning positive voltage.
For example, green colour on TD implies positive voltage for 'Transmit Data' and red colour implies negative voltage for TD, Green colour on RD implies positive voltage for 'Receive Data' and red colour implies negative voltage for RD.
Seven LED's indicate the status of the following data lines;
TD ---- Transmit Data
RD ---- Receive Data
RTS ---- Request To Send
CTS ---- Clear To Send
DSR ---- Data Set Ready
CD ---- Carrier Detect
DTR ---- Data Terminal Ready
Links to the stores where these RS-232 Mini Testers can be bought:
1. Triangle Cables.com LLC:
RS-232 Mini Tester from Triangle Cables.com LLC online at http://www.trianglecables.com/mintesrsdb25.html>
Trianglecables.com LLC18735 East Colonial DriveSuite 112Orlando, Florida 32820U.S.A
2. CNC Speciality Store LLC:
RS-232 Mini Tester from CNC Speciality Store LLC online at http://cnc-specialty-store.com/rs232-cables/rs-232-mini-tester-with-led-indicators-db-25-male-to-female
CNC Specialty Store LLC1318 Colonial DriveWatertown, WI 53098U.S.A.
3. CWC Groups:
RS-232 Mini Tester from CWC Groups online at http://www.cwc-group.com/rsmite.html
CWC GROUP1290 E. Acacia StreetOntario, California 91761U.S.A.
4. Newark/element14 [Premier Farnell Canada Limited]
TS500A-R2 - DB9 Pocke Tester at Newar/Element14 online at https://canada.newark.com/black-box/ts500a-r2/db9-pocke-tester-2-7-h-x-1-2-w/dp/02J7762
Newark/element14Premier Farnell Canada Limitedc/o T27537 PO Box 4275Postal Station "A"Toronto, ONM5W 5V8Canada