RS232 Master and Slave not synch

[janem]

Hey DL community

I have got a problem with my rs232 modules.. my schematic consists of two rs232-input modules with 16 channels each. If I want to do an 2 channel operation with e.g.. Channel 0 from master and channel 0 from slave an errors occurs that the data stream is not synchronized. How can I synch them?

[CJ_Butler__DASYLab_Pro]

Hmmm....

I recall something like this years ago, and the explanation is now lost.

Can you connect the RS232 channels to a Write Data module using the DDF DASYLab format, and post a minute or so of the data in a zip file? 

I think that you need to look at the RS232 settings and force it to use a Timebase setting, rather than the timing from the individual readings. Look at Options in the RS232 Input Master.

[janem]

Hi, no sry i cant upload  the data, because i'm not at work right now... 

but i try to explain more:

first thing is, DASYLab V8 is used.. idk whether there are new functions in V12.

My external measurement device is sending data with ~2hz without any data demanding.

I think I already tried to set them on blockwise with own timebase but there was no difference. So i thought to write the data of the RS232 instantly into global variables and then reading them --> same time base..

but then i found out (attachment), that there is a data loss with the method of GV's (home-simulation with generator sending 2 hz voltage): Every part is running with global sample rate of 10hz. Why there is a difference between the two versions?

Is there any other possibility to synch the devises? shifting register e.g.?

[CJ_Butler__DASYLab_Pro]

V8 has the same feature, but the words are different.

The Generator typically uses the Driver time base, and the Gl. Var Write is writing once per block.

So, to see all values, you must have a block size of one.

I set up the Driver timebase to 10 Hz, block size of 1. The Generator and the Read Variable default to the Driver timebase.

The Generator is making a 2 Hz Rectangle waveform. YOu can see that it's shifted, but otherwise intact.

[janem]

Yes that works, thank you.

So that could be, theoretically, a possible solution, to sync Master and Slave? Or is there anything to fear with this solution? I think you can change the GV from outside, which could be a problem if you overwrite them somehow, right?

[CJ_Butler__DASYLab_Pro]

I think that it's a good solution. I use it for other scenarios where I cannot directly connect the inputs and outputs.

The other solution.... the Special group has a Signal Adapt module that can fix things.

Usually... fix at the source is the first option. Anything else is a fix, and can lead to unwanted behavior. For now, I think that the Variable solution is a good one for you.