heaters synchronizing

[becidea]

Hi, I have two heater. These heaters are controlled by Lakeshore 336temperature controller (336). 336 has two heater control unit. 100W and 50W, heaters are 25 and 27 ohm resistances. These heaters are standing opposit eachother with the distance about 10mm.

I need to control both heater via feedback from thermocouples so close to the heaters. I need to create tmeperature gradient between heaters and try to keep this gradient from room temp. to the high temp. 800K. 

how can I make heaters synchronizing. I made vi but there is no heaters synchronizing and also sometimes one heater is not seen by my vi.

The problem is that one of the temperatures show 0.00, but there is no pbolem with the 336 bacuse display show that its normal. I don't know why but, when I push "highlight execution lamp" button in block diagram, there is no problem; however, if I don't push this button one of them is not working. what can be the problem?

[becidea]

this is the vi and you can see the result on *.png file....

[becidea]

so no one can help me!!!

[Brian_A]

Hi becidea,

It sounds like you have a race condition when reading the temperature. Try reading the temp sequentially rather than in parallel. 

<Brian A | Applications Engineering | National Instruments> 

[becidea]

hi, Brian_A,

I see your point but I don't think so because I have also a vi, which works simultaneously with my main vi. in this vi i can read both temperature simultaneously like display of 336.

[RavensFan]

How come the screenshots you attached appear to be from a different VI than the VI that you attached (which is missing several subVI's)?

It certainly looks like you have a possible race condition in your attached VI.  You have two parallel paths each using the same VISA resource.  How do you control that when you write and read that the reading you get back is for the data you expected when you did the write?

[becidea]

leave it screenshots and concentrate on vi I sent second. Please find 336 drivers attached for missing Sub vi'. Fan,  I don't understand your question!. I use two output's of 336. I control via chosing "output control loop 1 and output control loop 2.  each of them controls each heater output. It is also related to reading.

The same VISA source you mentioned and parallel structures. there is one machine and two source, Output control  loop 1-2... Measneously.urements shoulde be simultane...

[RavensFan · Accepted solution]

Both of your Single Reading subVI's near the end of the loop have input D wired up to them.  So it looks like they are each trying to read the same channel.

You don't have automatic error handling turned on in your program (VI properties/Execution) and you don't have anything wired up to the Error output of those subVI's.  How do you know you aren't getting a timeout error or something like that?  Re-enable automatic error handling, but especially but some indicators on those error wires.  You are probably getting a communication error on one of those such as a timeout, and it is returning the default data of zero.

[becidea]

I see, there are errors handling but I didn't put like I didn't chance C and D. 1. thermocouple reads C and 2. is D. When I send I guess I changed. But problem is not because of this actually. 

[becidea]

Thank you Fan, yes yes, The problem  is actually case as you said. thank you alot;)