help with a-b PLC

It really just depends on how fast your flow is and how many pulses/liter you have your flowmeters set up for. The 1746-HSCE only has one input, the 1746-HSCE2 has 4 inputs. You may be able to get by with a fast input card or even a normal input card, depending on your application and your scan time.
Steve

Spectrum Controls, an AB, partner has a card designed specifically for flow meters, the 1746sc-CTR8, take a look at this LINK
I've used the 4 channel card on several occassions, it is similar to the 1771-CFM module for the PLC-5.

hi guy's and thank's for the reply .
one thing i forgot to say : i use a remote i/o configuration with 1 master rack and 2 slaves racks ( with only i/o cards). all 3 racks gets flowmeter data.
my flowmeter give up to 40 pulse/sec (at max).
i check on the 1746sc-CTR8 datasheet and it says this card can't function on a remote i/o configuration.
now i don't know if any fast digital i/o will be good because the remote i/o configuration ... any other sugestions?

I have used a 1746ITV fast digital input card with an absolute encoder, so it should be fast enough for a flowmeter totaliser flow pulse. Not suitable for a PWM flow signal. Using a totaliser flow pulse is more accurate than taking an analog flow signal or a PWM flow signal and doing the integration in the PLC, as there will always be errors. Let the flowmeter do the integration and give you a pulses per litre signal as I think you want to do anyway. A standard software counter will work as long as the combined input response time and the scan time is less than the fastest pulse period.

but does the use of the fast i/o card 1746- ITV on the remote i/o rack will be helpful? (does the cpu scan the remote i/o as fast as the local one ?)

to remind you i use cpu SLC-5/03 and i got 1 master rack and 2 slaves with an universal i/o protocol ...
the max rate of the flowmeter is 50 pulses/sec .

With a period of 20mS I think the remote i/o communication may be too slow or perhaps borderline. It may be better to use a local PLC such as a ML 1000 and collect the data via an AIC and DH485 network to the SLC 5/03. The local PLC does the counting and passes the count on. A ML1200 may be better but more expensive as the compactlogix 1764 DI module has an input response time of 1mS. If you didn't want to use DH485 then DF-1 over RS232 may be fast enough if your SLC serial port is not already used.

I would contact Spectrum about using thier flow meter card, the manual states that the card cannot be used in a remote rack because of the size of the input and output data. However, you may be able to overcome this by using a series C processor and block transfer reads/writes. I have found that the Spectrum support is very good, and wouldn't write them off until I contacted someone in the tech. support department.


If your only concern if flow rates, not quantity, then perhaps a pulse to analog converter might work. There are several brans on the market that convert pulses to 4-20mA, then you could use analog input modules.

You should be able to use the 1746-HSCE module in a remote rack, and it would be able to keep up with the pulse rate. Check the manuals for your meters and the HSCE2 to make sure they're electrically compatible.

HSCE

HSCE2