Send command button – change register bit

[cooldjmc]

Hi, please if some one can help me if is possible to send command to change only one bit in a modbus register and not modify other register bits. For example if i have one register 0110 0110 1000 0110 and i want to change only the second bit to 0 is is possible to use one Button to send command (something like SetBit? )?

Thanks.

[Mikhail]

Hi,

Set a formula for the output channel.
Something like this (not tested):
(ushort)Val(101) | ((Cmd > 0 ? 1 : 0) << 2)
There the input channel #101 stores the current value of the register.

[cooldjmc]

Thank you Mikhail for your quick response, i will try that and post the results.

Have a nice weekend!

[gabeirinhas]

when I use this formula in the output channels.

(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 0)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 1)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 2)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 3)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 4)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 5)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 6)
(ushort)Val(321) | ((Cmd > 0 ? 1 : 0) << 7)

For 1 byte I get the activation of each of the channels without losing the value of the channel.

I need to know how to do the same but to disable each of the bits.

I use command type: standard

I use command values: execute

Is there any way to activate a specific bit of the byte with a formula or with off-on without losing the byte values.

Thank you

[gabeirinhas]

Basically I need to know how to disable the bits without losing the rest of the byte values.

[Mikhail]

Try, for example

Cmd > 0 ? ((ushort)Val(101) | 0x0002) : ((ushort)Val(101) & 0xFFFD)

0x0002 hex is 00000000_00000010 binary
0xFFFD hex is 11111111_11111101 binary

• This reply was modified 1 year, 4 months ago by Mikhail.

[gabeirinhas]

it works

Thank you very much for the help

[manjey73]

public double SetBit(double n, int index, double setvalue)
{
long nn = Convert.ToInt64(n);
return setvalue > 0 ? nn | (1 << index) : nn & ~(1 << index);
}

I do not know, is this what you need or not? Just writing a bit to a number. You need to add Formulas to the Reference Books

[gabeirinhas]

Mihail’s solution is perfect for me.

Thanks for the help

[Mikhail]

Solution provided by @manjey73 is more generic. We will include SetBit function in the configuration template.

[victorlam]

(ushort)Val(101) | ((Cmd > 0 ? 1 : 0) << 2)
what’s the meaning for the formula used?

[manjey73]

@victorlam In this case, in the existing channel 101, you change the 2nd bit to 1 if it was zero, or it remains 1 if it was in 1 and you write 0

| – or
<< 2 – Shift the zero bit by 2 positions

That is, this formula is only for setting the 2nd bit to 1

• This reply was modified 9 months, 2 weeks ago by manjey73.

[manjey73]

If the setBit formula has already been added to the database, it allows you to change the bit to both 0 and 1

SetBit(Val(101), 2, Cmd)

When transmitting 0, bit number 2 will be reset, when transmitting 1, bit number 2 will be set. The remaining bits of the channel will not be changed

[Author]

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