modus library differences ?

[LV_Pro]

I've been using the NI Modbus library contained in "ni_modbus_1_2.zip, downloaded from NI. I've noticed recently another zip on this site "nimodbus121.zip. Are there any differences that anyone is aware of? I haven't done a serious comparison, they are the same size, just wondered why there are two different pages devoted to the same library, under different zip names?

[JeffL · Accepted solution]

Hi LV_Pro,

That is strange...as long as your version contains LabVIEW 8.6 and the Readme says 1.2 from January 2008, as far as I know you have the 1.2 version.

[Christian Mergl]

Hi,

Could you post the two links to the different files, because I was just able to find the one containing the "nimodbus121.zip".

Christian

[LV_Pro]

Well it appears that some how I saw an old page (which I now can't find) and a newly updated one. I may have left a tab open in my browser to the old one, then opened a new search, I've have done that before. I do find reference in the new page that make reference in the text to the old zip, "Version 1.2 (ni_modbus_1_2.zip) of the MODBUS LabVIEW Library is backward compatible" even though the clickable link is for the nimodbus121.zip. Both zip files are on the ftp site so I guess that my using the "Wayback machine" may have caused my confusion.

[RavensFan]

Is there any listing of what has been changed between the 1.2 version of the library and version 1.1?  I didn't see anything in its readme file.

One thing that jumps out at me is that it appears to be using polymorphic VI's.

Are there any other differences?  Any bug fixes to be aware of ?

[Ben]

Hi Putnam,

I just want to pass a long a possible "heads up". One of my co-workers used a modbus library he found on the NI site a while ago. It functioned but was implemented without any waits in the loops so it ended up starving the CPU when run on a cFP unit.

So check for waits in loops if the CPU is being pounded.

Take care,

Ben

[RavensFan]

In a recent thread, a user noticed a problem with the way MB Serial Init was programmed.  It has to to with the way it configures the data bits, stop bits, and parity depending on the Modbus mode you are using, and those settings do not match the modbus guide and may not match the device you are working with.

[LV_Pro]

Thanks, all. Guess I will spending this week going through the modbus "stuff". Saw a thread, which I didn't tag, which talked about a problem with a timing problem that might be the cause of an issue of getting random timeouts from an instrument (Lighthouse mini-manifold, a 6 port air sampling manifold), where I ended up putting in code to clear the timeout error 6101 and retry, up to a preset retry limit. Unfortunately the customer decided to send the unit back today, so I'm dead in the water for trying out changes. I noticed, in digging down into it, that the modbus stuff is stacked sequences, etc. Would probably fail the CLD exam!

[Ben]

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LV_Pro wrote:
Thanks, all. Guess I will spending this week going through the modbus "stuff". Saw a thread, which I didn't tag, which talked about a problem with a timing problem that might be the cause of an issue of getting random timeouts from an instrument (Lighthouse mini-manifold, a 6 port air sampling manifold), where I ended up putting in code to clear the timeout error 6101 and retry, up to a preset retry limit. Unfortunately the customer decided to send the unit back today, so I'm dead in the water for trying out changes. I noticed, in digging down into it, that the modbus stuff is stacked sequences, etc. Would probably fail the CLD exam!

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Yes that sounds familiar. Find all For and While loops and make sure there is at least a "0 ms Wait" in all.

Ben