Communication with many RS-232 instruments.

[labmaster]

Dear,

In our lab, we have more than 10 RS-232 instrument.

Each instrument, which is monitored the data by Labview usually, positioned long distance (around 10 meters).

Recently, I am planning to control the instruments by labview in one computer in simple connection wire arrangement.

Is this good idea to use several converter of RS-232 to TCP controller for this work? 

( I have never used the converter)

If so, how to control the converter?

For example, should each converter have the unique IP address?  

or how to send the RS-232 command? Need some more instruments such as Lan hub?

Any good idea or comment should be welcomed.

Thank you.

Lee

[Brian_Beal]

What baud rates are you running at?  10 meters really isn't very long for lower baud rates.

[Makoto]

> If so, how to control the converter?

Normally the control method of LAN-Serial converter may have two cases, 1)the device driver provides a virtual COM port therefore you access it as COMx port, 2)the device is simply controlled using TCPIP socket.  I am sometimes using Lantronix XPort product and this is the second case, then the baudrate/data/stop/parity/flow etc are configured by device's acompany utility.

> For example, should each converter have the unique IP address?  

It depends on product specifications. If the LAN-Serial converter is "single COM port" type (very typical case), you will have to have 10 units of this, then each unit will have different IP addresses. If the Lan-Serial converter has "multiple COM port" all in one unit and these COM channels are separated by TCPIP Port#, the converter will have only one IP address.

> or how to send the RS-232 command? Need some more instruments such as Lan hub?

If the LAN-Serial converter provides virtual COM port, you can use any RS232 library such as Microsoft MSCOMM, LabVIEW's Serial VIs, or VISA Library's Serial IO support.  If you access the LAN device directly, you can use Winsock Library, LabVIEW's TCP/IP VIs, or VISA Library's TCPIP-SOCKET IO support. No need to have more instruments, but normal LAN Ethernet HUB may be required for solving physical LAN connections.

[Anonymous]

On Feb 7, 10:10 pm, labmaster <x...@no.email> wrote:
> Dear,
> &nbsp;
> In our lab, we&nbsp;have more than 10 RS-232 instrument.
> Each instrument, which is monitored the data by Labview usually,&nbsp;positioned&nbsp;long distance (around&nbsp;10 meters).
> &nbsp;
> &nbsp;
> Recently, I am planning to control the instruments by labview in one computer&nbsp;in&nbsp;simple connection wire arrangement.
> &nbsp;
> Is this good idea to use&nbsp;several converter of RS-232 to TCP controller for this work?&nbsp;
> ( I have never used the converter)
> &nbsp;
> If so, how to control the converter?
> For example,&nbsp;should each converter have&nbsp;the unique IP&nbsp;address?&nbsp;&nbsp;
> or&nbsp;how to send the RS-232 command? Need some more instruments&nbsp;such as&nbsp;Lan hub?
> &nbsp;
> Any good idea or comment should be welcomed.
> &nbsp;
> Thank you.
> &nbsp;
> Lee
> &nbsp;
> &nbsp;

Some friends of mine in the lab used Moxa's DE-311 or personally I
will recommend NPort 5110.
And if in your lab, wireless LAN is allowed, then you can even use
Moxa's NPort W2150.
Connect all the instruments' serial port to that serial to ethernet
box then connect that box to LAN. Then install the driver by Moxa, you
will
get more com port in your desktop or laptop. Labview will recognize
those extendded com ports and communicate with them without any
trouble. Hope this could help.

[Brian_Beal]

I guess I need to clarify my response.  If you are using relatively low baud rates, I would add com ports to your computer.  I have always used products from B&B Electronics, whether it be PCI cards or USB converters.  The easiest would be the USB to 232 converters, and with a 10' USB cable, you can decrease your 232 cables by 3 meters.