Why is the TCO output of the PCD2.H110 not detected by the interrupt input of a PCD2.M480?
In the manual of the PCD2.H110 you can find an example of automatic period measurement where the XOB 20 is used for reading the measurement continuously. This example doesn't work on a PCD2.M480 due to it's input filter of the interrupt input INx that is connected to the TCO signal of the PCD2.H110.
Since the signal of the output of the PCD2.H110 in measuring mode "perjod-automatic" is only high for 1.6 µs it is very hard to detect it. As the interrupt input is optimized for recognising signals with 1 kHz (50/50 % duration of high/low states) the duration of 1.6 µs is too short to recognise this TCO signal.
As workaround it is suggested configuring the TCO output in mode "static-normal". As this isn't possible in automatic measuring mode, the measuring mode has to be changed to "period-manual".
To achieve a continious measurement you'll have to start a new measurement in the XOB20 (after reading the measured value).
There is no problem detecting the TCO output as long the module doesn't work in automatic measurement mode since in this cases the TCO is high for more than 1.6 µs.
PCD2 / Hxxx
Last update: 04.04.2015 09:32
First release: 06.07.2004 18:32