Hi,
I have a dt800 which i wish to connect a number of energy meters to. the energy meters have a pulse output of 100p/kWh. my intention is to use a counter channel on the dt800 to accept the pulse output from the meters and also send this reading to a channel variable. within another channel variable i intended to scale the input by the simple equation 1CV=2CV/100 which should give me kWh. i am unfamiliar with the energy meters and counter inputs as i have not programmed these before therefore am i correct in my setup intention and will i have to log the meter pulses every second to be correct.

Stephen...

Good morning Stephen,

That would work but it would be simpler to use the first two terms of a polynomial to scale your data, that way you don't need to use channel variables.
100 pulses per kW means 1 pulse = 0.01 kW. The first term in a polynomial is an off set and the second is the scalar (Slope)

First set up your polynomial
S1=0,0.01"kW"

Then in your schedule apply the polynomial to the counter
1C(S1)

Cheers

Roger

Hi Roger,
Thank you for your reply i will use the span as suggested.
Will i have to set the schedule rate to 1 second for the pulse input, if so i would consider setting the schedule with rate of 1 second to working channels and use cvs whereby i can then use a separate schedule with a 15 minute rate to log the returned kWh. Simply to minimise the amount of data logged.

Stephen...

Good morning Stephen,

Do you need both the 1 second data and the 15 minute data? If so then that is a good approach.
If you only need the 15 minute data then simply set the schedule speed to the 15 minute rate and reset the counters.

Cheers

Roger

Hi Roger,
Thank you for the reply. I only require 15 Minute data therefore i will set the interval to 15 min. With respect to resetting the counters does the reset need to coincide with the interval or should i reset at at particular time or quantity, i take it i simply enable reset on the counter channel and set the wrap to the required number. also i need to log the total accumulated kWh over the time of the project approx 12 months therefore how would this best be achieved.

Thanks,
Stephen.

Good morning Stephen,

To reset simply use the reset channel option (R). It will display the counter value the reset to zero.
Don't worry about the counter wrap value, you don't need it.
To keep a tally assign the reading to a channel variable with the +=nCV channel option.
+= will add the new value to the current value in the CV.

I would save the running total every day. Do be aware that with the current firmware if you reset the logger you will loose the running tally.

Cheers

Roger

Thanks Roger,
below is what i have done with the reset and an alarm to turn logging on and off between certain times.

1C(R,"IN01",+=1CV)
2C(R,"IN02",+=2CV)
3C(R,"IN03",+=3CV)
4C(R,"IN04",+=4CV)
1CV(S4,"INV01")
2CV(S4,"INV02")
3CV(S4,"INV03")
4CV(S4,"INV04")
ALARM1(3ST("Logon")><8.,19.)"Logon"{[LOGON]}
ALARM2(3ST("Logoff")<>8.,19.)"Logoff"{[LOGOFF]}

Hi Stephen,

You can apply the span in the counters
1C(R,"IN01",+=1CV,S4)
2C(R,"IN02",+=2CV,S4)
3C(R,"IN03",+=3CV,S4)
4C(R,"IN04",+=4CV,S4)

Cheers

Roger