Support for 3rd Party I/O

[Software_Monkey]

I am thinking of using Labview 8 for a data acquisition system I am installing but I cant find anything on using 3rd party I/O modules. The instrument driver library lists many multifunction instruments but not basic I/O.

I wish to be able to connect to Wago 750 series industrial I/O either directly or via OPC. Has anyone any experience of this? Will I have to write my own driver?

Thanks

Tony

[JamesC]

Hi Software Monkey,

I suggest you read through this tutorial on how to communicate with the WAGO modbus I/O.

Hope this helps
Regards
JamesC
NIUK AE

[unclebump]

It kind of depends on how fast of a sample rate that you need. In labview 7.1, I was acquiring data samples every 5ms inside a Momentum plc and using the plc registers as a data buffer. I'm not sure if labview 8 has changed how fast this data can be received. I think you can probably get at least 100ms sample rate.

[malef]

Tony,

we are running 3 test benches with the WAGO 750 system and LabVIEW. The first application is talking via OPC-Server from WAGO to the ethernet controller. OPC is easy to handle but produces a large overhead which results in some limitations similar to DataSocket. www.kepware.com sells a nice OPC-Server for about $800 if I recall correct. It's fairly universal. WAGOs OPC-Server costs about $350.

Communication to WAGO-I/O-System is Modbus based. Modbus is supposed to be 20 times faster than via OPC. But you have to worry on your own about things like: How to manage modbus calls from different locations of the program. Meanwhile NI publishes a free, downloadable library for Modbus communication. I think it is a beta release of a future toolkit or will be part of PDS. Some critcal remarks about this library:
- library can only be installed under LV 7.1 - with some work I down-/upgraded them to 7.0 and 8.0
- examples don't make use of dataflow programming and error trapping
- simulating a slave is faulty
- no documentation
Nevertheless our nevest bench is talking Modbus TCP/IP to a WAGO coupler. I modified some VIs and have a robust communication.

All above is also valid for serial Modbus communication. There are several threads about modbus in the forum.
For instance:    http://forums.ni.com/ni/board/message?board.id=170&message.id=151337&view=by_threading&page=1

Manfred

[unclebump]

What kind of samples rates can you obtain with this setup??

[malef]

Maximum sampling rate is about 250 samples/s with Modbus TCP/IP.
But A/D conversion time of modules is about 80 ms.

Manfred

P.S. LabVIEW 7.0

Message Edited by malef on 12-22-2005 12:51 PM

[Software_Monkey]

Thanks for the replies guys. I am not looking for great speed but I would hope to be able to do (say) at least 10readings/sec. I know can acheive much faster rates than this using my own OPC client.

Each channel is sampled only every 30 seconds so the conversion time of the Wago A/D isn't an issue for me but there are about 300 channels and I would like to keep the time skew between the first and last channels to a minimum.

Thanks again for the help.

Tony

[unclebump]

Thanks Manfred. Could you show us some code??

[MartinPaulick]

For the WAGO-I/O-System there are some additional application notes available on the WAGO homepage

1) Configuring WAGO Ethernet with National Instruments LabVIEW via ModbusTCP (2005-03-15)

http://www.wago.com/wagoweb/documentation/app_note/a2016/a201602e_f.htm

2) Configuring WAGO Ethernet with National Instruments LabVIEW via Lookout OPC (2005-03-15)

http://www.wago.com/wagoweb/documentation/app_note/a2016/a201601e_f.htm

3) Configuring WAGO Ethernet with National Instruments LabVIEW via CoDeSys OPC Server (2005-03-15)

http://www.wago.com/wagoweb/documentation/app_note/a2016/a201603e_f.htm

4) Configuring WAGO FireWire Coupler 750-339 with National Instruments LabVIEW 7 (2005-03-15)

http://www.wago.com/wagoweb/documentation/app_note/a2035/a203500e_f.htm

5) Configuring National Instruments LabVIEW with WAGO I/O (2002-10-09)

http://www.wago.com/wagoweb/documentation/app_note/a2014/a201401e_f.htm

[buckovski]

Hi Manfried,

As I'm reading your posts I can see thet you are very experienced in comunicating with WAGO equipment. I'm new in this so I need some help. I'm using LabVIEW 7.0 and trying to connect to wago 750-341 via Modbus TCP/IP. I'm using the standard vi's downloaded from wago's web but I'm receiving error 56. What is the problem and what should I do to fix it?

Best regards,

Aleksandar.