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What is using my COM port?

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I am trying to get ProWorks NxT to communicate to a 984-685E. I have the correct cable, but when I try to communicate, the comm light on the processor doesn't even blink. I can use RSLinx to get the light to blink, showing that the port and cable are functioning, but NxT does nothing. The vendor says that there is probably another program using the com port. I have completely disabled RSLinx (which works fine for SLC/PLC5 comm). Is there any way to determine what might be using my com port?

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What version of Proworx NXT? What version of Windows? What other PLC software is installed. RSLinx is usually the culprit as it takes over the com port and boots with Windows in most installations. Make sure NXT is set for the proper serial parameters (baud rate, RTU/Ascii, etc.) and the right COM port.

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I can use Hypreterminal to make the comm light blink as well. This should prove that nothing has exclusive control of the com port. I've tried every combination of port settings alllowed, checked to make sure the IRQ and memory are set up "typical" on this machine. NxT is 2.1, OS is XPPro SP1. There are too many other PLC programs loaded to begin mentioning (RS5, 5000, 500, Omron, Siemens, DL, etc.).

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Do you have activesync installed on your pc? It also has a habit of grabbing the comm port and not wanting to release it. Dale

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If you are able to use Hyper Terminal with the specified port, it means that there is no other programs using and locking your port. You can not connect to the port locked by ActiveSync program by HyperTerminal. ActiveSync can not be the problem. Is your computer a lap top? I know that some lap tops have different pin configurations other than standart rs232. You may search in OMRON forums for this kind of problem. I remember such a problem in OMRON forums in this site. Is your serial port is a real serial port or do you use a USB to RS232 converter? Some converters may not work at all, even they can lock the PC and show you the blue face of death screen. Sometimes, serial ports may burn. For example, I am using a PC that TX pin is OK but RX pin burned. I can sens but can not receive. Can you use your serial port with other devices and softwares? To test your TX -RX pins, open a Hyperterminal session without handshake. Communication speed is not important. Short circuit Pin 2 and Pin 3 of your computers serial ports pins with a jumper. If your serial port is OK, you will see on the screen of HyperTerminal what you typed on keyboard. Best Regards,

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Quickest way to check for a functioning port if it's a it's a 9pin interface is to plug an old serial mouse into if (if available). You'll also what to ensure that the application was designed to be used within win2k/xp (i don't know the prog your using...I new to controls) because what happens with alot of legacy applications is they try to access ports directly and they can't.

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