Hi. I am new in forum.

I made a LabView program that allows me to set the analog and digital outputs of the DT800. When I set the values with a control in the front panel there weren't problems but when I tried to program a PID controller to set the VO value after a while it stopped working out.

I founded in this forum and with the deTransfer that I was receiving the E55 error message. So I made a reset (I don't know if that is the correct way to solve this) and all works again. So my question is what can I do to make my LabView program to set the VO value every loop iteration without the memory fills.

I don't know if every time I send a command from LabView it gets stored in memory or something like this. Sorry for the long message but I tried to explain the problem clearly. Thanks in advance for your help.

Martin

Good morning Martin,

This is from the DT800 manual:
E55 - Expression memory full

• Memory for storage of expressions text is full (total is 16384 characters, shared with alarms text)
• Reduce number of expressions

It's not an error you would normally expect to see unless you tried to enter very large equations.

What code are you sending to the DT800 to run the output?

Cheers,
Roger

Hi Martin,

Which VIs are you using within the loop? Are there particular VIs you are using to write the command? If you wish, I can have a quick look over your LabVIEW code, however I am using LabVIEW version 8.0.

The ideal VI to use to write the command, would be the advanced VI, "Write Line to Datataker"

Cheers,
Anthony

Hi.

datataker is running a job to read some themocouples. In LabView I have programmed an event loop to manage the actions performed from the control panel.

In the timeout event I use the datataker write line to datataker VI from the datataker lowlevel driver to send the VO=X command to control a 3 phase power controller and I use the read line VI from the same library to read the data scanned in the current job running in the datataker. Also in other control events I use the same VIs to send the commands VO=X and DO=X to open and close a relay.

I prefer to explain in words because my VI is getting very large and hard to understand (I have some routines to communicate with a PLC too). But anyways I could send you some pictures of it.

I guess every time I send a new command to the dataTaker it is stored in memory so maybe I could have to clear this memory periodically but I'm not sure. If you could give me any advice it would be great. Thanks.

Martin

Hello everybody,

Maybe I've became in a kind of boring person that is always talking about the same thing but actually I am stuck with this problem. So I appreciate so much if any of you that are more experienced than me could help me.

Reading the DT800 users manual I could get some information about what's happening. I have a current job with one schedule running on the datataker that I send once with the DeTransfer. Then I send commands to the datataker pushing some buttons in my LabView front panel.

So, as far I understood, every time I send a command, the DT800 performed the action and appends the string to the text located in a reserved part of memory (shared with alarm action text). So it has 16384 as total number of characters it can store.

In a note wrote in the page 99 of users manual you can read:
"There is no garbage collection in this text space. That is, new text is appended to existing text in the text space, and superseded text is only removed by a system reset."

So my question is how can I do to change analog output or a digital state output value from a supervisory computer. Maybe I have to do a reset or do a deljob periodically in order to continue sending commands. I think it wouldn't be the best solution to a very common task as supervisory and control can be. Or maybe I am doing something in a wrong way.

Anyway thanks all of you for reading my long, long reply.

Cheers.
Martin

Hi Martin,

I am trying to simulate your problem in the office. Could you please email me an image of the VI? where you are writing the VO command, and reading the response?

Email the image to sales@datataker.com.au

Cheers,
Anthony

I am following up this topic offline, and I will give a summary of what has been found.

Cheers,
Anthony Ulrich