simple Formula that compares an Integer or real and returns Boolean

[Hennie_Kotze]

Good Day,

Please give me a simple formula that will compare one real value with an Integer, and return the “Calculated Discrete” channel as ON or OFF.

I read a real value into channel 60. I want to compare this value with the fixed value of 33. If the value in Channel 60 is equal to 33, then the virtual discrete channel must be 1, or true, or on….

Thank you,

[Mikhail]

Hi,

Try this:

Val(60) == 33 ? 1 : 0; Stat(60)

However, it’s a bag practice to compare floating point values by equality operator. It’s better to use <= or >=

[manjey73]

It is not correct to compare the real number, simply because it can fluctuate within certain limits, for example, 32,999-33, 019, and then you will have the output turned on and off. You need to apply Hysteresis to avoid this. Kind of laid out the formula of Hysteresis on the forum.

[manjey73]

Hysteresis added to Formula tab

int[] HysNum = new int[1];
bool[] Hys = new bool[1];
public double Hysteresis(double inCnl, double low, double high)
{
bool q = Val(CnlNum) > 0;

int res = Array.IndexOf(HysNum, CnlNum);
if (res == -1)
{
res = HysNum.Length;
Array.Resize(ref HysNum,  res+1);
Array.Resize(ref Hys,   res+1);
HysNum[res] = CnlNum;
Hys[res] = q;
}

if (inCnl < low) Hys[res] = true;
if (inCnl > high) Hys[res] = false;

return Convert.ToDouble(Hys[res]);
}

In the channel, use the formula Hysteresis(Val(X), 32.5, 33.5))
Where Val(X) is your measurement channel. Enabling and disabling the output is already configured for the channel in which you use the Hysteresis formula

[Hennie_Kotze]

Thank You Guys…

The channel 60 is defined as a REAL, but I’m actually just reading one modbus register. The value in this channel is just the decimal representation of the word, and is actually just an Integer….

The first code ” Val(60) == 33 ? 1 : 0; ” works like a charm!!

Thank you!!

[Mikhail]

In Rapid SCADA all input channel values have the double type. Double is a 64-bit floating point.

[TDE]

Hi Henni,

Can u please show me how you define it in the channels table?

[Author]

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