Micro 1400 High Speed Counter Setup - Please help!

[TimD]

Hello,

I have used counters to totalize flow before, but never the high speed counter.

I have a flowmeter, which has a pulse range of say, 0 - 10,000 pulses per second. I am using the dedicated high-speed pulse inputs (not 4-20ma) in the controller.

Fortunately, the Micro 1400 has 6 available 100 khz counters, which easily cover the above range.

I have the Micro 1400 Reference manual, but after dozens of pages explaining the Function File for HSCn, it only lists two instructions. One is HSL, the other is RAC. RAC is very self-explanatory, it resets the accumulator. HSL is a bit worrisome to me, since it's listed as an output.

My question is, How do I set up the HSC for proper reading, and TOTALIZATION? I will be totalizing gallons of liquid used, and I can figure out the scaling OK, but never set this kind of thing up.

Please help!!! I'm using Logix 500. Many Thanks!

Tim

 

[bkottaras]

Not a Totalizer but this may help with the HSC.
Rather old but came in handy a couple of times.

 

[bernie_carlton]

TimD - your application will be very similar to the one shown except that, in the STI program, you will be adding the HSC total (or more likely a scaled version of it) to a grand accumulated total before resetting the HSC.

 

[TimD]

First, Thanks for the replies!

So you guys are saying, that I will be resetting the accumulator every interval, I'll call it every second. Before I do the reset, I am storing the totalizer value somewhere (probably a float?) since I want to 'extend the life' of the totalized value.

I see the STI function file, but there is only one, does this matter that I have six hsc inputs?

I'll check into the docs on STI and get back to you. I'm hopeful now! hope to talk more tomorrow.

Thanks Again,

Tim

 

[bernie_carlton]

In the single STI ladder simply read/store/clear all 6 of the HSCs each time interval (second?)

 

[TimD]

OK, got everything set up exactly as described, then math overflow every time.

The flowmeter isn't even moving and I get an accumulated total greater than LONG after 1000msec. (2,147,483,647)

I set up both HSC2 (input currently wired to) and STI:0, as well as an additional LAD file (3) for the STI instructions.

I'll keep looking...

 

[TimD]

Knew it was something dumb.

OK, now pgm runs, but I do not see flowmeter action, i.e. no totalization.

I'll re-check wiring. Is there any other instructions to read the input? Or should I see an accumulated value in mou HSC input file (while in RUN) that resets every second?

Thanks!!

 

[bernie_carlton]

In the I/O config (while offline) check the CPU - Adv Config - Embedded I/O Configuration (I'm hoping this is similar to the 1100 since I don't have update RSLogix) - Input Filter. Make sure it is a short enough time to allow the pulses. You'll ahve to re-download if changed.

 

[TimD]

Hi Bernie, thanks, I changed the filter to 5us (lowest I could).

I verified that I have a current sinking device wired appropriately. I do not see any blinking on the controller's input LCD display under the input number. I'll go with the manual wire trick to see if I can energize the input and get the acc to increase that way. If so, then I have to look harder at these flowmeters...

Thanks!

 

[TimD]

Got It!

Need a 2.2k ohm pull up resistor for current sourcing, even though I can wire the controller for sourcing or sinking.

It appears my enclosure was wired for sourcing, so I don't know why the resistor is needed. Oh well, it works accumulating now!

Now I have to figure out how to scale these inputs...

 

[hem]

Dear All:

I need to measure encoder pulses, I have mIcrologix 1400 + Analog i/p card 1762,
my first question is, I need to put my encoder wire in Micrologix 1400
or in Aalog i/p card 1762 !!

regards,
hem