Adding a scale to SLC 5/04... Help?

We are looking to further automate my mixing operation by adding a check scale before my mixer.

I am looking to do this on a tight budget, preferable with indicators I already have.

How can I read those scale outputs on my SLC 5/04? And make accurate scale readings? The only systems I have seen are Hardy scales with RIO or Mettler Scales with RIO. Using RIO would require new indicators.

Can the RS 232 be used from my existing indicators?

Thanks

JP

I've used Mettler scales with analog out (4-20mA) from a display that I inputted into a small PLC's analog input card.

It's a little pricey to buy the display, but it did everything I needed. It was easy to set up, scale the output into engineering units, etc. I looked at the RIO unit, but that seemed like overkill.

You did not state what RS232 scales you have and what they can output, if they can do ASCII then it may be possible. It may also be possible if their RS232 can be configured for a protocol..Modbut RTU etc etc.

I prefer the RIO scales for PLC-5 applications, but for SLC's it is a little over kill. You should be able get ASCII output from the scale RS232 port into the RS232 port of the SLC. It will take a bit of programming in the SLC to convert the ASCII text, and you will have to configure the PLC port for ASCII input. You didn't mention the brand of your existing scale displays, but most of the major brands can be upgraded by simple daughter board additons. I use mostly Metler-Toledo and they have boards for almost anything you can think of, ethernet, analog, devicenet, modbus, etc...

I recommend you contact the mfg. of your existing units, find out the options available, at the very least get a manual (if you don't already have one) for the units. It should give you an example of the ASCII output string. You will need this when you convert the string to a number.

Regards,

Ken

We use 4-20 mA with our scales.
The load cell transmitter has 4-20 mA output wich goes to a normal 4-20 mA input in the PLC.

You might want to look at Hardy Instruments; they make wiegh-scale modules for AB PLC's.