Note that pin 3 on the 9 pin RS232 connector is the Transmit Data (DATA OUT) and pin 2 is the Receive Data (DATA IN). On the 25 Pin RS232 connector pin 2 is the Transmit Data and pin 3 is the Receive Data (THEY ARE REVERSED!). NOTE THAT THE MOST COMMON PROBLEM IN THIS PHYSICAL CONNECTION IS HOOKING A TRANSMIT DATA(TD) LINE TO AN OTHER TRANSMIT DATA (TD) LINE, two outputs when hooked to each other can not transmit or receive data. This must be clear, it is not the pin number that is important, it is the FUNCTION of that pin on that particular connector. TD is always transmit data or DATA (OUT). RD is always receive data or DATA (IN). The data flows in to the RD and OUT of the TD line.
Also note that the pin numbers on all connectors are on the connectors themselves in extremely small print next to the pins themselves.
After you have a working physical interface between a PC and the sensor/robot, then it is only necessary to “T” into the functioning circuit with a MONITOR device. A monitor devices is passive, it only “LOOKS” at the transmit/receive data lines. Shown here is a Benedict Computer DLM200, but any monitor can serve the purpose.
If you don’t have a program of your own on the PC to exercise the sensor/robot , you may want to use HyperTerm or some other terminal emulation program in the design testing phase. If you use Hyper Term, then on your PC start HYPER TERM. Under FILE, Properties set the “CONNECT USING” to “DIRECT TO COM 1” or whichever COM port you are attached to. Following the manufacturers instructions, set the proper parameters on the line monitor. E.G.., 9600 baud, 8 data bits, 1 stop bit.Select configure. If your monitor has an autoconfiguration feature, you may execute this function instead of manually setting up the monitor. You should now be ready to send data through the circuit and monitor both sides of the conversation between the PC (controller) and the sensor/robot. The line monitor can allow you to view the “conversation” in ASCII or HEX or other representation. Most monitors have a search function and timing functions to time how long (in milliseconds) it takes for a response after a command is sent. Many other options may be useful depending on the system you are designing.
Click for information on BENEDICT COMPUTER
hand held RS232 / RS422 MONITORS.