Host Engineering Forum
General Category => Do-more CPUs and Do-more Designer Software => Topic started by: Garyhlucas on January 08, 2019, 08:46:06 PM
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We switched from Do-More Terminator with a CTRIO card to BRX and were caught off guard by BRX only having 3 high speed counters built in. We have 4 flow meters that pulse too fast for general inputs, what to do?
I set one of the high speed inputs to trigger an Interrupt. In the interrupt routine I count to ten, pulse a C bit and reset the counter to zero. that C bit drives a FreqTmr block at a rate that works in our 5ms scan time and we have the flow rate we need. Seems to work pretty good so far.
Anyone see a problem with this?
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Good save.
I had to look and see because I was thinking of a job we had 3 H2-CTRIO2 modules for 3 axes (1 per axis, though 2 modules would have worked.) A single BRX could have done all three with Step/direction and quad encoder feedback too. I was thinking 8 high speed inputs, but I see the 3 counter restriction.
It must be a very busy program to run 5mS on a Do-more. I put the PLC scan time on the C-more on the 3 axis job and it runs around 2.5mS. I usually forget to look at the scan time on while on start-ups.
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New BRX HSIO module coming in the next few months.
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I just noted the scan time when I was trying to solve this problem so no effort has been made to see if it could be better. We have about 10 analog inputs, 4 high speed inputs, 4 pulse outputs, that are not real fast, and 5 VFDs on PID loops communicating via Modbus, and a C-More that does continuous logging of data. My suspicion would be that the way I implemented Modbus is huge resource hog. I do use stages everywhere possible.
One thing to consider is that our product is a tiny membrane waste treatment plant rated at 10,000 gpd but the reality is it has virtually identical I/O to a 5 million gallon a day plant, so maybe not too bad.
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Any time line for the HSIO?
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Soon. I'll send you a PM.