Modbus sent single value bit

[TomasIha]

Hello, maybe you can help me, how can I send the value only to 8bit, because if I use this script everything works, but it also activates 1bit as an example.
I want to send the value only as an example 8bit

require('luamodbus')
mb = luamodbus.tcp()
mb:open('10.30.0.242', 8000)
mb:connect()
mbetslave(1)

bendra_reiksme = mb:readregisters(1000)

function setbit(value, bitnr)
  local mask = bit.lshift(1, bitnr)
  return bit.bor(value, mask)
end

value = setbit(1, 8)

mb:writeregisters(1000, value)

mb:close()

[admin]

Try this:

Code:

require('luamodbus')
mb = luamodbus.tcp()
mb:open('10.30.0.242', 8000)
mb:connect()
mb:setslave(1)

value = mb:readregisters(1000)

function setbit(value, bitnr)
  local mask = bit.lshift(1, bitnr)
  return bit.bor(value, mask)
end

value = setbit(value, 8)

mb:writeregisters(1000, value)

mb:close()

The recommended approach is to use profiles.

[TomasIha]

This script is the same as mine. How can I send a value of only 8bit, because now 1bit is momentary, and when I send a value of 8bit, it also activates 1bit

[admin]

This script is the same as mine.

It isn't the same (left is original, right is modified):
   

[TomasIha]

Hi, I tried this script. Everything works, but when this value is sent to the modbus register, the other bits of the modbus address also receive values ​​and trigger other device functions. How can change only 8bit value

[admin]

Check if your device supports function code #22 (Mask Write Register).

[TomasIha]

If I find out that it supports it, maybe you can give an example of the script