Holding a reading

[jeremy1973]

I will be using DaqFactory to read an A/D board. Is it possible by digital input signal to hold the value for say 30 seconds and then resuming reading from the A/D board? This is a mudlogging application and I need to do this while I change dilutions on my gas detector to give time for the sensor to settle back down to the correct value after the dilution change - otherwise bad data would end up being logged.

[AzeoTech]

Sure, you can set the Timing of the channel to 0 for that time. You'd create a sequence to do this, something like:

myChannel.Timing = 0

channel.restart()

delay(30)

myChannel.Timing = 1

channel.restart()

Then in the event for the digital input, you just call beginseq(myseq) to start that sequence and stop acquisition on myChannel for 30 seconds.

[jeremy1973]

I actually plan to have a five position radial switch with a position for each dilution setting and with each setting a TTL routed to a different digital input port so the computer knows which setting it is on. Could this delay sequence be triggered by the change in input port/setting value or will I need a seperate dedicated digital input switch to initiate the delay?

I should add I'm very new to this.

[AzeoTech]

You can have multiple digital I/O's trigger the same sequence. Just put the same event code in all the digital inputs. The code would look something like:

if ((digIn[0] != digIn[1]) && digIn[0])
  beginseq(myseq)
endif

[jeremy1973]

Thanks. That makes sense. One more question though:

Rather than stopping acquisition for 30 seconds can it be made to hold and keep sending the last value read before the 30 second period? Somehow get it to keep supplying the last value read for 30 seconds? I still want to transmit that value serially during this 30 second period kind of fooling the system to think the reading is steady for that 30 seconds. Does the stopping acquisition for 30 seconds do this?

[AzeoTech]

Sure, its just slightly more complicated:

myChannel.Timing = 0
channel.restart()
private starttime = systime() + 30
while(systime() < starttime)
   myChannel.addValue(inserttime(myChannel[0], systime(), 0))
   delay(1)
endwhile
myChannel.Timing = 1
channel.restart()