Distech's FPCs: math with SNVT_temp_p

[maffooclock]

I hope this is the appropriate section...

Years ago, Distech came to us for a demo. Me and another programmer played with the Free Programming Tool and determined that Distech's BASIC implementation was a joke, so we stayed away from Distech and stuck with Circon. Now that Circon has gone belly up, I'm forced to re-create some of our controls solutions using Distech's controllers.

Anyway, I've got a problem with arithmetic on a couple of setpoints:

nviStptCoolOcc is a SNVT_temp_p with a value of 76.0
nviStptCoolDiff is a SNVT_temp_diff_p with a value of 0.99

I want to add these together for calculating demand for cooling, but I get strange results; I expect 76.99 (or something close -- you know how number act on Lon stuff), but instead, I get 2721.

Seems like my only workaround is to change these back to SNVT_count, but I don't want to! Can someone please tell me what needs to happen so I can do math with SNVT_temp_p data types?

By the way, if anyone has a recommendation for a controls manufacturer who is comparable to Circon other than Distech, please speak up!

[sysint]

Isn't there GFX an improvement to their basic? I can tell you even that will seem somewhat constrained to Circon basic. Plus, the controllers don't have the OV's that Circon controllers had either. Maybe see what Smart controls can do to help you.

On this Distech programmable I can only remember guys talking about values. You probably have the decimal points off so you get a screwy result. Probably have to account for C as well.

BTW- I see you are Loytec users. You should check out our new web servers, particularly if you want to convert over some NI/VI jobs. Distech offhandedly suggested using an ilon for this but that would not too functional by comparison.

It's amazing to me how many guys really like much of Circon but management found a way to tank it anyway.

[maffooclock]

I saw the EC-gfxProgram in SmartInstaller, but didn't know what it was. I'll have a look at that.

I am aware of the decimal issue, but thanks for watching my back!

We also use TAC's Xenta controllers, and I really like those (except in projects where Vista Workstation is not the front-end, then creating NV's for every little thing just to get data in another UI is a pain in the ass). But using a 401 + the other two modules it would take would cost too much when compared to Circon or Distech controllers.

Circon wasn't my favorit as far as DDC goes -- I never understood a logic circuit with slow-blow fuses. Circon's controllers seemed to fail more often than anything else (although we have a few sites where we've got 5-year-old controllers that have been there since the day we left site). I wish we'd just put in Andover Continuum, but I'm just a programmer, so I wasn't asked...

Anyway, back to the topic: thanks, sysint -- I appreciate your time and effort. I'm still looking for an explanation on why I can't do math with those NVs, or an alternative to Distech altogether.

[ctrlguy]

I want to add these together for calculating demand for cooling, but I get strange results; I expect 76.99 (or something close -- you know how number act on Lon stuff), but instead, I get 2721.

Well, 2721 is the correct answer! Distech Freeprogs use integer math. To get reasonable resolution, they multiply everything by a factor. In your case, degrees F are converted to Celsius X 100. So 2721/100*1.8+32=80.978°F.

If you have access, you should download http://www.distech-controls.com/Log-in/Tech_Notes/05DI-TECH100-01.pdf

If your controller is compatible, by all means, use the new gfx program. It is vastly superior and eliminates most of the math issues. If you're going to upgrade a controller, get the tech note on that too.

[maffooclock]

I was pretty sure 2721 was actually 272.1 or even 27.21, but I still didn't know how to get that into 76.99 and it didn't occur to me that might be Celcius. Thanks!

By the way, I've installed EC-gfxProgram via SmartInstaller, but hell if I know where it is. It doesn't show up as a plug-in that can be registered (I use NL220 as my LNS tool). Doesn't show up in the Start menu, either. Hrmm...

But before I get too froggy, I need to make sure I can even use that with the EC-67 and ECP-400.

But, so far, my problem is solved, thanks to ctrlguy. However, I am still interested in other ideas as far as controllers go. I did check out Smart Controls (and a few others), but I couldn't find anything that showed Smart Control's devices are LonMark certified -- I read the cut sheets on a few of their controllers, and I also check Echelon's product database.

[sysint]

It's official. I'm the red-headed step child... On the Distech gfx software-- I think that you need the "new" line of progs for the graphical software.

[maffooclock]

Well, the conversion works... sort of. Yes, the math is correct, but it just makes things harder in the programming. [sigh...] I'll just change them all to SNVT_count. They're just setpoints, and they aren't being bound.

F%^$*^! Distech. Thanks, fellas.

[dapper]

It will not work with the EC-67 but will work with the ECP-400. Depending on how old it is you may have to up upgrade the ECP-400 to allow gfx programming.

[maffooclock]

Thanks, dapper! These are both fresh out of the box, ordered just last week.

[ctrlguy]

Don't be too quick to condemn Distech. They're one of the few (only?) products that cram a fully programmable controller into a Neuron chip with a free LNS plug-in (and Tridium wizard) to make it work. And the gfx program is exceptionally intuitive. If you want to see it, register the plug-in in your database and create a new device using one of the templates (eg "Distech Controls ECP400-410 gfx v3") then launch the plug-in and see how easy it is to create a program.

[crab master]

The other thing to throw out there is I've worked with a few Distech ASC's and there plug-ins were awesome compared to many others. They also had features such as optimized start in the ASC itself, just send it a SNVT Time of Day Event or whatever it was and it would then calculate optimized start, and configurable and scalable inputs so you weren't as limited on the thermistor ranges.

[sysint]

...They also had features such as optimized start in the ASC itself, just send it a SNVT Time of Day Event or whatever it was and it would then calculate optimized start, and configurable and scalable inputs so you weren't as limited on the thermistor ranges.That feature was stolen from somebody else first...

[crab master]

I wish some others would steal it as well!

I've sent other manufacturers screen shots of the plug-ins and links to websites/downloads saying look they are doing it better than you are!

Anyway IMO if a manufacturer makes a plug in easy to use with a good product then the product is more likely to be installed and setup correctly. Some of the plug-ins/browsers that I've dealt with...uggghh! And then people wonder why it never worked correctly, too difficult to setup and some of the ones I've found setup wrong, I can't overly fault the guy on not setting it up correctly. You've gotta be more of a computer programmer than HVAC guy just to run the plug-in. Point being if an intelligent HVAC service guy can't setup the plug-in then the manufacturer needs to go back to the drawing board and make a better plug-in. Not to hijack this thread but it's frustrating to me that I just can't have the service guy do a balance/setup on an asc w/o extensive training.

[foyler]

Well, the conversion works... sort of. Yes, the math is correct, but it just makes things harder in the programming. [sigh...] I'll just change them all to SNVT_count. They're just setpoints, and they aren't being bound.

F%^$*^! Distech. Thanks, fellas.

How about type SNVT_temp_diff_p. Had to do this in other lon programs for math equations and it prevented conversion and kept the units of measure.

[maffooclock]

You all make good points and I agree -- there are plenty of things worse than Distech.

Crab Master said "You've gotta be more of a computer programmer than HVAC guy..." Well, I was a programmer before I even knew what HVAC meant. Circon had it's annoyances (like not storing the source code in the controller and having to license the damn compiler!), but I was pretty comfortable with making it work -- it's BASIC implementation was very extensive. Now it seems like Distech is my only option at this point, and it makes me sick. I've written some crappy code, but not because I'm an inferior programmer, but because I have no choice! And the lack of dedicated OVs for the I/O? C'mon!

Distech is appears to me to be a really great idea, just implemented poorly. I know Distech is buying Circon, but I don't expect they'll keep Circon's products at all. But it would be a dream if they combined the good things from each.

Okay, I'll step off my soapbox now.

[crab master]

No stay on the soapbox - it's conversations like this that get people/manufacturers thinking. You like the better code as you come from a computer programmer background, but my point is in the end it will likely be a HVAC service guy working on it so put it in a format he/she can understand. Don't use some kind of code words to tell with the Discharge Air Temp, or the Compressor command/other is, ie Line 5 bit 12, 1=ON, 2=OFF. I've watched more service guys get frustrated with this.
I can also understand your logic as well, as personally in many cases I would rather have a PLC than an ASC in many instances because if there is something that isn't operating quite the way I want to I can just fix it and not have to wait for the manufacturers' update.

[maffooclock]

Well, in our case, our techs don't touch programming -- most can barely get around in Windows, let alone work with LNS apps and plug-ins. But I get your point :)

I've almost got a 1-cool, 2-heat, dehumidifier program working. It's not too bad, actually, but I feel so "icky". I sure hope I don't have to write a complicated multi-chiller sequence with one of these.

I am interested in the EC-gfxProgram, though (although, not for this EC-67)... Anyone with Menta experience who can compare?

[crab master]

I deal with Menta a lot. My email is in my profile; however I haven't dealt with the Circon/Distech programmables.

[sysint]

... I sure hope I don't have to write a complicated multi-chiller sequence with one of these.

I am interested in the EC-gfxProgram, though (although, not for this EC-67)... Anyone with Menta experience who can compare?Maybe look into our LINX110 or 111 for that task. IEC61131 programming. 1000NV's so you won't run out.

[oakbranch1]

If you did not order the controllers with the GFX option you will have to reflash the app to run GFX. But I do like the GFX much better than the distech line by lie tool. Ex-Circon