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MD4 refresh rate for specific variable using 6.08 IQANdesign
We would like to update a specific variable on the MD4 at a frequency of 4 Hz, rather than at every change based on the MD4's 50-ms cycle time.
How can we do this in a simple and optimized way?
Customer support service by UserEcho
What do you mean by 'update'? is it a variable being sent over CAN, or a sensor input, or a display item, something in the measure groups, or a log item? A J1939 Frame can be set to send on a trigger which can be an IDC set to True and a 'delay on' of 250ms and blocking condition of itself. A Sensor input can't really be changed; it updates every cycle. if you want a display item you can have a MEM channel memorize the value you are looking for with the same IDC described for the J1939 as the trigger and display the result as a value Item. Measure Groups are the same, just put the MEM channel in the measure groups you want to view. For the log, put the variable in an event log as a Value Log Item, then use that IDC as the Activating function.
something like this.idsx ??
that appears to function to me. any combination of delay on and off will work so long as it adds up to the Frequency you need, personally I tend to use a delay on to the full amount (250 in this case), as that leaves the signal to act more akin to a leading edge trigger. If you change the MEM to add instead of replace, you can watch it count up at about 4 Hz