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Old January 16th, 2006, 05:45 PM   #1
Puerto Rico

piscis is offline
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Problems with KEPDirect OPC Server and Laptop

I downloaded the demo software and install it on my desktop and my laptop computer. I built a small Quick Client with four Data words and five Outputs connected to a 05 PLC. My desktop computer, which has a serial port, had no problems reading the actual values in the Data words and updating the five Outputs almost in real time.

My laptop computer with its USB to Serial converter had problems and could never read the Data words and update the five Outputs. Has anyone had any problems using this product with laptop computers? Is this a USB to Serial converter problem? I use the exact same setup for both computers. I also borrow a brand new laptop and had exactly the same problem.

Please let me know your experiences with this product.
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Old January 16th, 2006, 05:52 PM   #2
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automatic is offline
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Go to Device Manager and make sure your port is 'COM1' and make sure you are using that in the driver.
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Old January 16th, 2006, 06:33 PM   #3
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Could be your USB to Serial converter. It is my understanding that USB/Serial converters are hit and miss on which products they will communicate with. So will work with AB products but not AD. So will work with AD but not AB. Others will work with both. I've never used one so I can't recommend one for you.
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Old January 16th, 2006, 07:33 PM   #4
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USB to Serial converters lack one feature that while not actually needed anymore, is often used in communication drivers, that being an interrupt.
I don't know firsthand about the KEP drivers, but you might want to contact their tech support and see if they require communication interrupts.

It's a simple thing, and actually, pretty unnecessary today with bufferring and in general, the speed that the COM ports are serviced, but still, many device communications drivers still want to see an interrupt line.

Another possibility, though even more remote, is that the driver is trying to thunk down right to the hardware. Windows (true) 32 bit systems will not allow that.

In most cases, a PC-Card serial port will work where a USB converter won't.
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Old January 16th, 2006, 08:23 PM   #5
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Another thing you might try is just sending a message via HyperTerminal from your laptop to another PC. I have seen situations where the voltage on the send/receive lines was too low for certain devices, and even cases where it would work if the laptop was plugged into AC power, but would stop working if it's running on batteries.

If you can send a message to another PC with this serial/USB converter, then you have to start analyzing the actual serial connection going to the PLC.
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Old January 17th, 2006, 01:27 AM   #6
rohan tandon
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i have used the KepserverEx (v4.0) to connect to S7 300 and micrologix 1000 through a usb to serial converter without any problems. I used a prolific usb to serial converter...

What operating system is loaded onto the laptop? Is it win xp sp2, if it yes then you need to configure DCOM settings for OPC server to work correctly...

hope this was of some use to u...
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Old January 17th, 2006, 06:49 PM   #7
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The OPC foundation has one of the better tech notes (they call it a white paper) on setting up DCOM with the XP SP2 O/S.
Using OPC via DCOM with Windows XP Service Pack 2

I personally suspect your USB to serial converter, but make sure that DCOM is enabled as described in the white paper.

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Old January 18th, 2006, 05:57 AM   #8
Puerto Rico

piscis is offline
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Thank you all for your great answers;

Plan A:

Do as Rohan said

“What operating system is loaded onto the laptop? Is it win xp sp2, if it yes then you need to configure DCOM settings for OPC server to work correctly...”

Plan B:

Buy a PC-Card serial for my laptop.

Thanks again great job!!
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