OPC via Modbus

A

Thread Starter

Amer

Hello,

I have some questions about connecting plc to opc via modbus.
The problem is that i don't have serial port on my laptop, there is only ethernet port (ethernet adapter).

Can I connect laptop directly to modbus hub via cat5 cable or i need some device between them?

I'm using Matricon OPC server for modbus, and Schneider's Modicon M238 plc.

Thanks a lot.
 
L

Lynn August Linse

Go to amazon.com or ebay, and buy yoruself a simple 'USB serial port' based on the FTDI chipset. They should be as cheap as $10.

You don't technically need the FTDI chipset, and I'm sure there are oodles of other USB-serial which will work just fine, but FTDI has been widely adapted & used, so you'll have the smallest risk for incompatibility. Companies even sell 2 and 4-port models based on FTDI, so you can gain COM1-COM4 if you like.

Best, the USB-serial ports 'survive' changing your laptop, so could last you a very long time.
 
>based on the FTDI chipset.

I second the nomination of the FTDI chipset.

Just today I installed a USB/RS-232 converter with an FTDI chipset on a Windows 7 box and it worked immediately, just like the others I've installed in the past 6 or 7 years.

In contrast, last week a colleague got stuck on a job out-of-state where he didn't have his FTDI converter. He wasted the better part of a day messing with a couple Brand-Xers that would stream 7 bit ASCII, even parity as anything but garbage characters. His third purchase was a converter with an FTDI chipset and it worked. Not all USB/RS-232 converters are equal, by any means.
 
>based on the FTDI chipset.

I second the nomination of the FTDI chipset.

Just today I installed a USB/RS-232 converter with an FTDI chipset on a Windows 7 box and it worked immediately, just like the others I've installed in the past 6 or 7 years.

In contrast, last week a colleague got stuck on a job out-of-state where he didn't have his FTDI converter. He wasted the better part of a day messing with a couple Brand-Xers that would not stream 7 bit ASCII, even parity as anything but garbage characters. His third purchase was a converter with an FTDI chipset and it worked. Not all USB/RS-232 converters are equal, by any means.
 
L

Lynn August Linse

I'd add that people do make USB-to-RS-485 converters! So you do not need a USB->232 linked to a 232->485 conerter.

Plus since a USB port 'normally' supplies up to 500mA 5v power, the USB->485 (even if isolated) is 'self-powered' ... but this will consume your notebook battery life.
 
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