Logarithmic chart recorder

[wideboydave]

I am hoping someone can point me in the right direction with a little problem: I wish to display Vacuum (range from 1x10+3mbar  to  1x10-5mbar) on a chart recorder with the time along the bottom. Vacuum is normally displayed with a logarithmic Y-axis. I can get it to display correctly on a Y/t chart, but then the x-axis does not display the actual time, but a relative time from the start.

Can someone tell me either how to display a logarithmic y-axis on a chart recorder, or get the actual time to scroll on the x-axis on a Y/t chart?

Thanks in advance.

[CJ_Butler__DASYLab_Pro · Accepted solution]

Change the Y/t Chart X-axis settings to use continuous, and change the type of display to time using time of day.

[wideboydave]

Dammit, that's so simple, why din't I see it!

[CJ_Butler__DASYLab_Pro]

Glad to help.

[wideboydave]

Have come across an interesting problem with this solution though... it worked fine in the test worksheet I set up, but when I integrated it into our main worksheet on the shopfloor, it didn't work properly. The Y/t chart X-axis wouldn't stay on 'Fast Recorder' mode (so it wouldn't scroll). After some fiddling around I found that it was to do with the Sampling rate, which on my test setup was 11.025kHz, but we have it set to 1Hz on factory setups. At 1Hz, the fast recorder mode will not stay on, in fact at any frequency other than that Dasylab picks to start with (it seems), the fast recorder mode doesn't work.

Incidentally, we found a 3rd way:

Use an Arithmetic module to get the log of the number and display that on a chart recorder, as to all intents and purposes that is the same chart as using the actual number and displaying it logarithmically!