Using cFP-1808 to extend the number of I/O modules accessable.

[Cheetah]

NI's advertising states that  ". . . you can extend the number of I/O modules controlled by a single NI 21XX controller . . . " using a cFP-1808.  What is the recommended LabVIEW method/function that should be used for this type of communication?  Ideally I would like to address the I/O on the cFP-1808 as if they were part of the main controller base.  Is this possible?  Also, is LabVIEW 8 required to use this feature of the cFP-1808?

[Otis]

Hi Cheetah,

I think that you can find the answers to most of your questions by taking at look at the cFP-1808 Quick Start Guide.

While you don't need LabVIEW 8 to run FieldPoint 5 (the version that offers support for the cFP-1808), you will be missing out on a lot of the really neat features of the latest version of FieldPoint and some of the best features of LabVIEW 8 such as the Shared Variable Engine.

Regards,

[Khalid]

A related question:  if I were to use the cFP-1808 as a Modbus Slave, are there Modbus VIs available from NI for this?  I know there's a Modbus example library available (submitted by a user?), but I am wondering if NI has developed any? 

Thanks,

-Khalid

[Otis]

Hi Khalid,

According to the Product Page for the cFP-1804  you can use ModBus with the cFP-180X, so ModBus will work for the slightly longer cFP-1808.

I did a search and found the ModBus Library for LabVIEW.  Those should help you out.  Make sure to check out this forum (near the bottom Michael C's post) for how to install it with LabVIEW 8.

btw, you've been rocking the FieldPoint forums lately, keep up the great work.

Regards,

[Khalid]

Thank you Otis.  The Modbus example library is good (and better than having nothing), but can definitely be improved a lot.  Hence was wondering if NI was coming up with one. 

-Khalid

[Cheetah]

Otis,

I looked over the Quick Start Guide in detail before my inquiry.  It sounds like in a round-a-bout way you said that the mechanism that NI's literature is referring to for this extension of I/O is the shared variable which I understand is new with LabVIEW 8.  Is this correct?  Also I have heard that the minimum recommended FieldPoint controller for hosting the shared variable engine is the cFP-2120.  Can you confirm this?  In the past we had used the cFP-2010 as our standard controller, but if we are interested in liberal use of shared variables it sounds like our standard should be the cFP-2120.

Thanks for your previous reply!

[Vincent_Carpentier]

Hey Cheetah,

If you are still wondering about your last question about using the cFP-2120 with Shared Variables, you are correct in thinking that it is better to use the 2120 if you are hosting the Shared Variables on the cFP unit (That means you need the Shared Variable Engine to be installed). If the variables are hosted on a PC or something else with more RAM, then you should be able to use your 2010.

<a href="http://digital.ni.com/public.nsf/websearch/2A2F5606C2ED888386257147005C676F?OpenDocumen">Why Do I Lose Communication with My FP-2000 or FP-2010 Since Installing LabVIEW 8.0?<a/>
And point 7 of this:

<a href="http://digital.ni.com/public.nsf/websearch/6E37AC5435E44F9F862570D2005FEF25?OpenDocument">Troubleshooting Network-Published Shared Variables<a/>

Vincent

[TommyTestBoy]

Cheetah -

You can use the Shared Variable to access the cFP-180x from your cFP-2xx0, however you can also use the FieldPoint API VIs if you have FieldPoint 5.0 or later installed.  If you save your configuration in MAX for both FieldPoint systems, then the cFP-2xx0 configuration as well as the remote cFP-180x configuration information will be stored on the cFP-2xx0.  You can then use the FieldPoint I/O Control along with the FieldPoint Read/Write VIs and get I/O from the 180x just as you would from your local I/O on the cFP-2xx0.

As far as the recommended FP Controller for use with the Shared Variable engine, the only FP controller that will NOT support the Shared Variable Engine is the [c]FP-2000.  The cFP-2010 and 2020 will support it, but you are right in that if you are interested in "liberal use of shared variables" that the cFP-21x0 will give you much better performance.

-Tommy