It is recommended that you first do a loopback test on a known good serial port. It is also useful for determining which COM ports are installed on your computer, and monitoring data transmitted by other devices, testing baud rates, etc.Īfter you run the loopback tester, hold the mouse over the various controls to get help. This utility is great for loopback testing because it has the ability to continuously send data out a serial port - you do not have to type anything, leaving both hands free to connect the transmit and receive pins on the device being tested. It will run on any version of Microsoft Windows that has the. See the link at the bottom of this article. You may save it to your hard disk or run it directly from our server. The download link is at the bottom of this article. Rather than use Hyperterminal for your loopback test, we recommend using our free one-man serial port tester. If the loopback jumper is in place, and you do not see your typing, something is malfunctoning or the jumper is not connected properly. This tests the port, the level converter device, and any connecting cable. The signal travels from your keyboard, out the serial port, thru the jumper, back into the serial port, and is displayed on the screen. If everything is working, you will be able to type something on the keyboard and see it appear on the terminal window. This is typically accomplished using a terminal program such as Hyperterminal. You may test a radio interface and your computer's serial port using this method.Ī loopback test simply sends data from a port, through a jumper, and back to the serial port. Easy to find in a pinch too.A loopback test is a simple way to verify that RS-232 communications hardware is working. USed some CAT5e for good distances for the 232 stuff also. It will be more subject to electrical noise. It might pay to try directly wiring 30m via RS-232 and see if it works. I'm not looking over your shoulder.Ĥ) It's the cable capacitance that limits RS-232 to a 50 ft (15m) limit, but I've lucked out and done 100+ feet (30m). A 2 wire RS-485 link will not respond to a hardwired loopback test because the tester shorts the (+) and (-) pins together and makes 485 dysfunctional.ģ) Unless you tell us what pins 2 and 3 and 7 and 8 are for both ends, it's a mystery. A loopback plug is not used in a working mode, it is only used in a text mode.Ī hardwired Loopback test applies to RS-232 only. A loopback plug is a substitute for a device on the end. Which 232 terminals or pins are needed for this to happen? Just Tx, Rx and signal ground?Ģ) A loopback plug is a test fixture to prove that what goes out from one end can come back again and be read by the send, given the right test setup. If you put the PC closer to the sign and connect it directly via RS-232, does it work?
1) If you are using two 232/485 converters, then the native communications must be RS-232 on both the PC and sign.
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