Read individual holding register

[ns.fariz]

Hi Mikhail,
I have successfully connect rapidscada to modbus device with function 3. And now, I have problem for reading some function, it’s explained that one modbus address can be divided to some output.

9
Mains low voltage
0
15
13/16-16/16

Mains high voltage
0
15
9/16-12/16

Bus failed to close
0
15
5/16-8/16

Bus failed to open
0
15
1/16-4/16

Please look above data, it divide 16 bit data to represent 4 output. How can I achieve that with rapidscada?

Sorry for my English, I hope I can explain it better.

Thank you for great software

[Mikhail]

Hi,

I’m not sure that I understand the question. But likely you need to create extra input channels of the Calculated real type. And use the Formula field of these channels to define the calculations.

[ns.fariz]

Hi Mikhail,

I need to read alarm from register offset 2048. But manufacturer put it 4 alarm at one register 16 bit. So 1-4 bit is High Oil Temperature, 5-8 High Coolant Temperature, 9-12 Low Oil Pressure, 13-16 Emergency Stop. And modbus device will return value from 0-15 depending on alarm condition. So I need to read 1-4 bit of register offset 2048. what formula it is I can use?

[Mikhail]

Hi,
The idea I wrote before is true.

For example, to get bits 5-8, you need a formula:
((UInt16)Val(101) & 0x0078) >> 4
where 101 is the source input channel.
Note: I didn’t test the formula.

[ns.fariz]

Thanks, I will try it.
But, could you explain what this code mean? I want to understand it, so I can use for another alarm.

[Mikhail]

This code performs bit operations. It uses C# syntax. You can find &, >> in C# documentation.
Val() gets the channel value.

[Author]

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