Internet PLC Forum
General => Technical support => Topic started by: Agradon on July 28, 2004, 07:48:52 AM
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Does anyone know what the T100MD+ processor clocks at? I was unable to find this info in any of the manuals.
-Gene
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Just found out that the processor clocks at 16 Mhz, finding out a little too late that the card is too slow for my application :-\
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The problem I am having is the fact that my application requires me to output at number to the PLC's outputs at a fairly high speed. I wrote the simplest program I could think of that would toggle one output bit on/off using the command "TOGGLEIO out1", "out1" being the name given to the pin output[1],0. I hooked up a probe to this output leading to an oscilloscope and ran the program, resulting in a peak speed of about 5ms per on/off cycle. With a 16 Mhz processor, the output should be able to update a lot faster then that, and I was wondering if there was any way of achieving this result.
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I'm not clear on what your app has to do but have you looked at the stepper or PWM outputs? They can achieve some pretty high frequencies.
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The TOGGLEIO only toggle the memory bit inside the controller. At the end of the ladder logic scan the PLC has to update its entire I/O bank in an I/O refresh cycle. The I/O refresh implements software debouncing technique to filter out glitches that could be introduced by noise and the I/O refresh time takes approximately 2ms. That is the main reason that the PLC is unable to toggle an output quickly. The minimum scan time of the PLC is therefore = logic scan time (approx. 10us per word) plus I/o scan time (minimum 2ms).
If you need to send out a fixed number of pulses, you may use the STEPMOVE command to achieve it.