digital input too fast to be registered?

[Blur]

Guys,

ever encountered a problem where the digital input is on for such a short time that the 888 did not register it? is currently working on a servo motor project. The omron proximity switch connected to the digital input failed to register occasionally when the bed driven by a servo motor went past it. The indicative light on the sensor went on and off as normal but the program fails to register. Any suggestions?

Regards

[support]

It depend on the scan time of your program. If during a certain scan the program spend lots of time at a custom function (such as executing large loops) then the scan time may stretch beyond the pulse width and the signal may be lost. Input signal that may come on only briefly should be connected to an interrupt signal which will run a custom function when triggered regardless of the scan time of the program.

[Blur]

How to connect to interurrupt signal? what's that? how to do? sorry for the question but I'm still learning.

Regards

[Blur]

Sorry but is it done by introducing INTRDEF ch, fn,edge at first scan? what does edge means?

Regards

[Blur]

If my PLC is in the midst of sending pulses out to a stepper and encounter the interrupt input, will the PLC carry on sending pulse? Or will the stepper stop in the motion and carry on only whem the interupt input is off?

Regards

[support]

Sorry about the late reply. Our server was down on Oct 24 due to power failure caused by hurricane Wilma hitting Florida. The server came back on briefly on Oct 25 after the backup generator was repaired but at 1:10pm EST the backup generator failed again so the server is down whole day.

Anyway, regarding your questions, the interrupt edge means whether it is from OFF  to ON (rising edge)  or from ON to OFF (falling edge).

While the interrupt service custom function is run, the stepper output generator will continue to generate pulses. It will not be hindered by the interrupt custom function.