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wiring for timer0 in mode2


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#1 Relais

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Posted 22 August 2011 - 12:03 PM

Hello experts,

we need a little help, because we are unsure about wiring the UE9-timer-FIO for our reflection-sensor in proper style. Sensor uses an open-collector pnp output, that is output +UB (here for us +24V DC, possible range are +10...+36V DC) or open. This +24V power supply is generated by an external unit.

We believe to know, in I/O-line the Rseries of 22k is necessary. But testing failed. Maybe there is a problem with the correct voltage-level for low-signal?

A test with +UB=10V and UNI10DIV-extension was successfully. The timer value on T0V displays a number of clock cycles if pulses are activated (rising edges).

The aim is now an uniform supply voltage of 24V DC for all sensors we have. Is there a simple possibility for wiring the pnp-output?

Thanks a lot and excused the poor english.

#2 LabJack Support

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Posted 22 August 2011 - 01:28 PM

Did you use a pull-down? When the PNP is open, you need a pull-down resistor to pull the voltage below 0.8 volts. When you have everything connected put your sensor in the active state and then use a DMM to measure from FIOx to GND and make sure it is >=2.0 volts. Then put your sensor in the inactive state and measure with the DMM and make sure it is <=0.8 volts. I suggest you use a 20k series resistor to FIOx, and then also have a 4.7k resistor from FIOx to GND. This forms a voltage divider when you drive it with 24 volts, resulting in about 4.6 volts on the FIOx pin. When your sensor is open the 4.7k will pull FIOx low to about 0.15 volts.

#3 Relais

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Posted 23 August 2011 - 12:58 PM

Thanks a lot, your suggestion hits the mark. Your resistor configuration works fine for +24V supply voltage. The optical sensor in conjunction with reflection faces (increments) is designed for mobile measurements of rpm's on large motor shafts (daylight mining giant equipment). Usually the rotation speed of whose main drives is never rising above an value of 1000 rpm (synchronous speed). There is also a very limited assembly area for additional measurement equipment. The cycle duration of pulse is in return the solid measure. Possible influences of errors or differences in positioning the reflection faces (e.g. 4) on the motor shafts we want to minimize by average determination the number of timer clock periods for at least 100ms. We believe it is the most practicable way in this case. Or is there an more favorable evaluation, has been overlooked by us?

#4 Relais

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Posted 28 August 2011 - 11:11 AM

Hello again experts, after we are successfully detecting time of oscillation of the rectangular signal transmit by the optical sensors, we have a further question. How to reset the timer? If the motor shaft slowdown an comes to a halt, the timer shows still his last value. So we always display rpm>0. We have to reset the timer, yes. We are working with "ProfiLab Expert" to create the logical connection diagram an frontplates for tracing, X-t-recorder and so on. The user guide UE9 describes for resetting timers writing a value of zero to the timer, but how? A constant value of zero on pin T0V (on UE9 symbol in profilab experts library) doesnt work. Thanks a lot for help and helpful hints.

#5 LabJack Support

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Posted 29 August 2011 - 07:09 AM

Yes, you need to write a Timer Value of 0. If it is not clear how to do that in Profilab you will have to contact them, but the general pseudocode is shown towards the end of Section 4.3.6:

http://labjack.com/s...ers-guide/4.3.6

Another option would be to use Modbus rather than the Profilab drivers:

https://forums.labja...?showtopic=4761


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