Internet PLC Forum

General => Technical support => Topic started by: rosssyscon on September 10, 2003, 06:03:39 AM

Title: Counter
Post by: rosssyscon on September 10, 2003, 06:03:39 AM

I am having some diffculty with the exact operation of the [DNCtr]. I am using it as a simple timer for a motor. When it times out, motor stops. I am using the built in Clk:1.0s to decrement the counter. I am using the SetCtrSV function to set the timer value.

Issues:
1) I need to be able to adjust the time on the fly. However, I can't seem to move a new value into the counter until it has been reset. ?

2) When the counter is reset, the CtrPV is equal to -01. Is there a better way to do what I am doing?

Thanks,

Title: Re: Counter
Post by: support on September 10, 2003, 11:11:08 AM

Normal use of a down counter is by means of the output coil  -----(CTR) instead of [DNctr]. The latter is meant to be a ring counter which will roll over to the setvalue when it hits zero.

When a counter is reset, it is internally loaded with -1. That's how it is represented.

You can change the counter value anytime by assigning it with a new value in custom function:

 CTRPV[1] = 123   ' set the present value of the counter to 123.