Pulse Output - - - - - Using DL06

Hi comrades,
I am looking for a slick way to program a variable pulse output on a Autom. Direct DL06 PLC.
The DL06 has a HSIO with pulse output MODE but the minimum frequncy is 10Hz which is too high for my application. My max frequency is 2Hz. The application is a neutralization system which measures pH value in a tank and adjusts the pH by sending pulses to a "LMI" metering pump which doses the reagent to the tank. The dosing is accomplished via a pulsing output (rel, PNP, NPN) which tells the metering pump at which frequency to stroke (volume per stroke is adjusted separately) min frequency is 0/min max is 120/min.

Thought about using internal clock 25ms and a counter......

Any Ideas ?

Thanks
O Jonsson

Orn Jonsson said:

I am looking for a slick way to program a variable pulse output on a Autom. Direct DL06 PLC.

Click to expand...

You'll need to use an A-B SLC processor if you want to write 'slick' programs...

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This sounds like how a temperature controller operates when in 'manual' mode, where the output's duty cycle is variable from 0 to 100%. Should be easy to duplicate.

Just use two timers to control the on/off time of the output. Use V-memory locations for the timer presets. Perform a little math on your analog value to scale the presets to the appropriate values. As your PH increases, the ON timer's preset will increase, while the OFF timer's preset decreases. Or is it the other way around?...

beerchug

-Eric

At 2 Hz (0.25 second on and 0.25 sec off) maximum, your best bet is to program two timers in your PLC that flip flop and reset each other as Eric suggested. The timer preset can be a variable equal to half the cycle time. Just make sure you have solid state outputs for the signal.

Another option is to use an analog output from the PLC and a voltage to frequency converter. You can get these from Omega Engineering, or Calex, or many others.

Try a Mitsubishi FX Series PLC. Has a PLSV instruction (Variable Pulse output up to 20 Khz). Also has a PLSR instruction(Pulse output with ramping)