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dcmoore817

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Discussion starter · #1 ·
Just to start this off went to training with lonboy at enerlon and it was EXCELLENT. would suggest anyone to take his course.

Im currently using a distech free programable controller (ecp 300) and am using line programing (basic)

the free programable controller has 18 nvi's of wich 17 and 18 are fan in. 17 is a high low select and 18 is an average.

i have bound 14 seperate nvo's all of the same snvt type - temp_p - from 14 different controllers and am unable to figure out how to extract the value into my basic program and get deg f.

in my program i basically write:

var_avg_zt = fan_in_av

fan_in_av when reading the help file from distech is the reserved word used to extract the data from nvi18.

i always end up with a real number and am wondering if anyone here might now a calculation to convert this real number into degf?

same with nvi17 but i need to convert the real number to lev percent?

thnks everyone
 
Discussion starter · #3 ·
got through the video and they touched base on the function of nvi 17 and 18 but no explanation as to recovering the data in your code.

i read the help files and the reserved words for doing these functions are

fan_in_av - to retrieve the average of the values
fan_in_hisel - retrieve hi value
fan_in_losel - retrieve lo value

i can use these but the data retrieved is a real number and not a converion to my desired value.

such as i say

var_avg_temp = fan_in_avg


and it returns a value of 18276 instead of 716 wich would be 71.6 degf. i know on all the other snvts i bring in such as state and tmp_p i have to use mathematical formulas to convert the raw value to a unit that is usable in my code.
anybody?
 
#4 ·
That number may be a total of all 14 bound variables?

18276/9*5+32=757.23805/10=75.72

Could that be the average of all your temps?

Sorry I'm not more help. I'm sure others will chime in sooner or later.
 
#6 ·
After thinking about it please disregard my math. I'm sure someone will answer soon.

I've never had any luck using temp_p's with the line by line controllers so I just just keep them snvt_count_inc and divide by ten.
 
#8 ·
Thanks for the pat on the back, DC... you picked up the material very well!

All LON control data processed by devices and sent across the network is in SI units. Seems to me that the old Distech controllers did not convert C to F very well. 381 had a good work around - also if the values must be only in SI units, maybe they can be converted at the head end.

Distech has a pretty good support crew and maybe you should give them a try. Are those old ECP 300's branded JC?

Cheers,
lb
 
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#9 ·
Right click on the nvi in the plug in, then edit, then help. This may explain what you need. Apparently there needs to be a multiplication factor entered in the code of the nvo device so all incoming nvo's are on the same scale. If the devices are ASC's I don't know if you can do that.

Here is a snippet from the help file.
SNVT_temp_p: which is used if you are trying to calculate a weighted temperature offset average (temperature values). Its scale is 1/100. So as explained above, to have the same scaling, a multiplication factor of 100 needs to be inserted into the code of each of the controllers sending an nvo to nviFP_18. An offset average is the average of the offsets of all incoming value from the configured setpoint. Ex: When using a normal averaging (all weights equal) with a setpoint of 22, the offset average of the value 21, 24 and 27 will be: ((21-22) + (24-22) + (27-22)) / 3 = 2.

I'm going to play around with my controller to try and figure it out. I was going to bind some space temps from some VAV's.
 
Discussion starter · #10 ·
lonboy - im using an lx300 wich is the equivalent of the ecp300. johnson does not want to support me because im using lonmaker instead of tridium and distech not so hot on me using lx300 on their support lines. im preety certain all in need is the mathematical equation used to strip the numerical value into a number usable bymy code.

381eng - i have read that file quite a few times and the multiplication factor they expressed is not doing so well in the code. tried all variations and still no luck. strongly appreciate your help here

basically im doing 6 schools right now that are all starting in a week and i have 5 unitsw that are vvt. im trying to do a supply air reset based on terminal load and a night setback setup on average temp. for now i have it doing a supply air reset on rat and will work for now so i set this issue to the back burner to keep other fires at bay. im still needing this resolved tho and am glad for all help that anyone has offered up.
 
#11 ·
I see what you mean, I bound 8 space temps from VAV's (ASC's) to nvi18 and the value displayed in the internal variable is around -485. My code reads (Load_Var = FAN_IN_AV) I then display the value of LOAD_VAR in an nvo and the value displays around 23. (I'm assuming degrees Celsius). What is weird is the value displayed on nvi18 is in degrees F.
I was trying to find a way to convert the convert the value of the nvo back to degrees F but ran out of time.

Hope that makes sense
 
#12 · (Edited)
Maybe this will help, these are the only two types oif input to fan_in_avg, try to understand the multiplication.

Sorry I can not be any greater help, but I never really used Distech's line code.

Percentage Average
(NV type should be SNVT_lev_percent)
Use if you are trying to calculate the percentage average
(terminal load values). Its scale is 1/200, meaning that, if
a value of 200 is given to an nvo, it will be read as 1%
with a network browser. The value of FAN_IN_AV
also follows this scale. So if you have 10 nvo (must be
from 10 different controllers) bound to nviFP_18, then
the value of FAN_IN_AV (or in the value field of
nviFP_18) will be equal to the average/200. The way to
avoid this is to insert a multiplication factor of 200 into
the code of each of the 10 controllers. So on these
controllers, the code VAR2 = VAR1 * 200 is inserted
where VAR1 is the value that needs to be sent and
VAR2 is the actual value sent, then the data source of
the nvo is set to VAR2. This way the value is multiplied
by 200 in the code and then divided by 200 when seen
78 Free Programmable Controllers User Guide
through a network browser. It is also divided in
FAN_IN_AV. Therefore the value that you read in the
value field next to nviFP_18 has the same scaling as the
ones (VAR1) sent by the 10 controllers.
This multiplication factor of 200 is applied only
when receiving data from a free programmable
controller. LonMark profile/application specific
controllers will display the correct value without the
need of a multiplication factor.


Offset Average (NV type should be SNVT_temp_p)
Use if you are trying to calculate a weighted temperature
offset average (temperature values). Its scale is 1/100.
So as explained above, to have the same scaling, a
multiplication factor of 100 needs to be inserted into
the code of each of the controllers sending an nvo to
nviFP_18. An offset average is the average of the
offsets of all incoming value from the configured
setpoint. Ex: When using a normal averaging (all
weights equal) with a setpoint of 22, the offset average
of the value 21, 24 and 27 will be: ((21-22) + (24-22) +
(27-22)) / 3 = 2.

EDIT: Further reading indicates that Offset Average is from a set point, I will try and post the whole section of the manual.
Kevin
 
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#13 ·
OK see FAN_IN_AVG starting on page 76, it looks to me like you can not get an average temperature, you can only do average percent load or avg temp offset from set point.

Kevin
 
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#16 ·
What you need is in this document.

Basically, AvgRmTemp_F= FAN_IN_AV /10*18/10+320. The result is F*10 so you get resolution down to 1/10th degree (Distech basic uses integers only) so if the average temp is 72°, the result will read 720 or so (there are rounding errors).
 
Discussion starter · #17 ·
THANK YOU!!!!! that appears to be what im looking for. im not going to have a chance to verify it for a few days but BIGGEST thanks not only to you but everyone here who has taken away from thier time to help me.


BIGGEST thanks
 
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dcmoore817
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