![]() ![]() If a field engineer is not available to create the physical loopback, you can configure a local loopback for the interface. This action is recommended because it allows you to test and verify the transmit and receive ports. To create a physical loopback cable can help to diagnose a suspected hardware problem. When selecting a suitable fiber loopback for the transceiver, we should consider the connector type, polish type, and cable type. Fiber optic loopback testing is the easiest way to ensure that the transceiver works faultlessly. Then we can compare the transmitted pattern with the received pattern to troubleshoot a defective node in the network. Thus, during the testing process, the loopback cable directly routes the laser signal from the transmitter port back to the receiver port. When performing the loopback test, the fiber loopback cable can be directly plugged into the output and input port of transceiver module respectively (the ports at the ends of the connection must be compatible). The former one is to send out laser signals and the latter is to receive signals. As we all know, transceiver module has two ports, a transmitter port and a receiver port. ![]() There are loopback plugs for many different ports, including serial ports, Ethernet ports, and WAN connections.įiber loopback cable is often utilized to check whether the transceiver module is working perfectly as designed. In a word, it is a connection device that is plugged into a port to perform a loopback test. It provides system test engineers a simple but effective way of testing the transmission capability and receiver sensitivity of network equipment. The lookback cables can provide a simple and effective means of testing the capabilities of the network equipment, and they are typically used for fiber optic testing applications or network restorations.Ī loopback cable is also known as loopback plug or loopback adapter, which is a plug used to test physical ports to identify network issue. Do you know the loopback cable can be acted as a test tool in the telecommunication? Absolutely, the loopback signal is used for diagnosing the networking problem. can anyone shed some light on this? plenty of descriptions of how to do a serial loopback test on the internet, but i haven't seen anyone with this problem.Īre there other pins that need to be bridged? do ibm computers run protocols other than rs232? do i need to bridge the terminals before starting the computer up, or is it ok to do so with the computer running? i've got the data bits set to 8, the stop bits set to 1, no parity bit, and i've tried both xon/xoff and no flow control.For testing applications, there are many tools for this function, such as visual faults locator, optical power meter, OTDR, etc. I figure, i've got to be doing something silly. com5 however displays the ascii that i've typed regardless of whether pins 2 and 3 of the db9 connector are bridged or not. com1 and com2, with pin 2 and 3 of the DB9 connector bridged, do not display the ascii that i've typed. there are three choices of com port in hyperterminal, so I went through each one of them. ![]() The second computer is a panasonic toughbook. Because I was not too sure whether this was the correct port being used by hyperterminal, and my cable is a DB9 straight through cable, I decided to try another computer. I've then bridged pins 2 and 3 together on the DB9 connector, and typed ascii text into the hyperterminal, but nothing has come back. I've opened up hyperterminal, and it has only displayed one choice of serial port. I have tried two computers, one an IBM clone desktop, it has two serial ports, one DB25 and one DB9, i'm trying to use the DB9. I need to check a serial communication circuit on a project I'm building (megasquirt 2 ecu) and I'm trying to perform a serial loopback test on the computer to verify that it is working correctly before hooking it up to the circuit board. ![]()
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