EGX300 - How to display Float32 measurements in a Custom Page

Adrian_Dicea · ‎2015-11-06

There are several resources describing how to create custom pages to display multiple devices in a same page, how to troubleshoot, how to dynamically display device registers without reloading the whole html page:

FA242825

63230-319-230a1.pdf

examplePLTags.shtml

exampleXMLHTTP.shtml

FA180074

FA273167

What I'm going to show here is not described in any documents up to now.

All the examples are referring to simple measurements of 1 register. This register is converted to a float value using another single register containing the scaling factor.

There are devices which use Float32 measurements, so that takes 2 registers. (1 register means 1 Modbus Register = 1 Holding Register = 16 bits).

So, the JavaScript code has to read 2 consecutive registers for each Float32 value, then it has to use EGX300's embedded JavaScript code to convert each group of 2 Registers into Float32 Data Values.

Here is an example of a static shtml page (refreshed by the meta tag every 2 seconds) that reads 3 values from a PM3255 meter which has Slave Address 14.

<html>

<head>

<meta http-equiv="refresh" content="2">

<title>PM3255 - Slave ID = 14</title>

</head>

<tr>

<td colspan="3" style="background-color: #A9A39C; width: 600px; text-align: center; font-weight: bold; font-size: x-large">PM3255 - Slave ID = 14</td>

</tr>

<tr>

<td style="width: 300px; text-align: center; font-weight: bold;">Frequency</td>

</tr>

<tr>

<td style="width: 300px; text-align: center; font-weight: bold;">Current</td>

</tr>

<tr>

<td style="width: 300px; text-align: center; font-weight: bold;">Voltage</td>

<td style="width: 100px; text-align: center">Volts</td>

</tr>

<tr>

</table>

</form>

<br />

function updateData()

{

// Read Registers (this is actually done when the page is served by the EGX300)

Registers =[PL__14^3010,3011,3036,3037,3110,3111__PL];

// Convert each group of 2 Registers into Float32 Data Values

CurrentAvg = ConvertIEE754(Registers[0],Registers[1]);

VoltageAvg = ConvertIEE754(Registers[2],Registers[3]);

Frequency = ConvertIEE754(Registers[4],Registers[5]);

// Put data on the page, formatting the text to fixed number of decimals

document.getElementById("current").innerHTML = CurrentAvg.toFixed(3);

document.getElementById("voltage").innerHTML = VoltageAvg.toFixed(1);

document.getElementById("frequency").innerHTML = Frequency.toFixed();

}

</script>

</body>

</html>

I hope this helps as a starting example for more complex scripts.

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Created on 6th NOV 2015 by

Adrian Dicea

Global Expert Technical Support Engineer - Support Prime PSE / EGX