Immediate input and STI

Hello,

I want to use counting pulses of an encoder with a PL5-processor
and using RSLogix5.
I know that there is an instruction IIN (immediate input) for
using with fast inputs.
Also is there a STI (Selectable Timed Interrupts).
Who knows how to use and make an example of this?
I am new of this for using fast inputs.

Greetings,

mulderm

Look at using a 1771-VHSC card. The card keeps up with the encoder count. Count is read and reset via block transfers. You can also reset the count with an external input. Encoder pulses are usually too fast for the PLC to scan the inputs solve the program and update the outputs before the next input goes high.

Counter

I am using an high speed counter moduile to count pulses. I basically take the input and run in to a counter. My pulses coming in from this meter are very low 28-30 pulses and the module can keep up.

As pointed out, your best bet to switch to a VHSC module especially if the frequency of the encoder is higher. The module is not cheap but can handle upto 4 different meters or encoders.

I don't have a processor or manual right in front of me but I believe it basically goes like this:

In the processor status screen there is a tab for 'STI'. Under this tab you configure various aspects of the STI function. The two big things you need to have are an interrupt interval (how often you want the interrupt routine to execute), and a designated program for the processor to go to when the STI is generated.

It's been awhile but, also in the processor status area is a tab to set up a hardware interrupt by designating a separate handler program and a discrete input.

Hi Mulderm,

A couple of issues to address:

1) How fast are the pulses comming in. If they are comming in faster than 100 Hz I'd consider the VHSC.

2) Put your discrete input module in the local rack.

3) Make sure you're using a discrete module with as small a propagation delay as possible (no filters on the inputs)

4) Use the PII and not the STI. The PII is a hardware interrupt that can be programmed to execute a program file at each event or after a number of events.

Let me toot my own horn here as an original member of the VHSC team, it's a great module and worth considering regardless. You may save some money on the hardware if you use discrete I/O but, depending on your application, you may pay more than the difference on setting up and programming a discrete I/O based system (vs. a VHSC based) system.

Good Luck,

(8{)} ( .)

(Yosi)

BTW, how did you make out with Access/OPC/RSLinx?

Thank you guys for the information.
I think to consider a VHSC module.
Yoshi, with the Access/OPC/RSLinx experiment works great.
I am now understanding, thanks again.

Greetings,

mulderm