homeLYnk V1.3.0 as a modbus tcp slaveserver

[Koen_Rowies]

Hello,

I am testing the AN016_V1.0 spacelynk as a modbus slave.

When updating KNX registers they are updated to the "slave modbus registers in HL" that works fine.

Now I want to update KNX registers when a modbus master writes to HL as a slave.

I used the code in the application note and slightly modified it.

When writing to MB register 1, 2 or 3 this need to be updated in the KNX group addresses 4/5/1-4/5/2-4/5/3, and thois part don't work

I did the test with PMC modbus to write to HL slave registers and this seems to work, when after writing i read these registers the value is updated.

But internally it is not send to the KNX group address...

PMC modbus write to HL as a slave

and when i read the registers with PMC modbus

But in HL they are not mapped to the KNX registers... therefore i use the code below, Modbus IP handler=>

------------------------------------------------------------------------------

-- modbus init

if not mb then

  --****************************************************

  -->>>>>>>>>Modbus slave setting<<<<<<<<<<<<<<<<<<<<<<<

  require('luamodbus')

  mb = luamodbus.tcp()

  -- IP:192.168.0.69, port: 502

  mb:open('192.168.0.69', 502)

  mb:connect()

  -- slave id

  mb:setslave(10)

  -- init slave storage for coils, discrete inputs, holding registers and input registers

  mb:setmapping(10, 10, 10, 10)

  --*****************************************************

  -->>>>>>>>>>>Register write callback<<<<<<<<<<<<<<<<<<<

  mb:setwriteregistercb(function(register, value)

      alert("register %d has been changed to %d", register, value)

      if register == 1 then

       grp.write('4/5/1',value)

      end

    end)

  --*****************************************************

   -->>>>>>>>>>>Register write callback<<<<<<<<<<<<<<<<<<<

  mb:setwriteregistercb(function(register, value)

      alert("register %d has been changed to %d", register, value)

      if register == 2 then

       grp.write('4/5/2',value)

      end

    end)

  --*****************************************************

    -->>>>>>>>>>>Register write callback<<<<<<<<<<<<<<<<<<<

  mb:setwriteregistercb(function(register, value)

      alert("register %d has been changed to %d", register, value)

      if register == 3 then

       grp.write('4/5/3',value)

      end

    end)

  --*****************************************************

end

-- server part init

if not server then

  require('rpc')

  -- incoming data handler

  local handler = function(request)

    local fn, res

    fn = tostring(request.fn)

    if not mb[ fn ] then

      return { nil, 'unknown function ' .. fn }

    end

    if type(request.params) == 'table' then

      table.insert(request.params, 1, mb) res = { mb[ fn ](unpack(request.params)) }

    else

      res = { mb[ fn ](mb) }

    end

    return res

  end

  server = rpc.server('127.0.0.1', 28002, 'mbproxy', handler, 0.01)

end

mb:handleslave()

server:step()

-----------------------------------------------------------------------

Another question, when defining the number of registers for -> MB:setmapping(10, 10, 10, 10)

Is this starting from modbus address 0 or will this mapping start from the first callback address...

What is the maximum number of registers that you would advise so HL would not get instable...

Kind regards

Koen

[sesa299442 · Accepted solution]

Hello Koen,

I have just test it with both version 1.0 and 1.1 and it works OK.

You are asking good question about the registers. It starts from zero in spaceLYnk.

It means that register 0 in sL corresponds to register 1 in your PMC.

When you map 10 registers using command MB:setmapping(10, 10, 10, 10),

10 holding registers is created, it means 0-9 in spaceLYnk point of view.

We have not performed tests for modbus slave load yet. But it is in our plan.

I cannot say maximum number of registers, but it is more about the modbus activity then count of modbus registers.

Even if you have 1 modbus resgister and you write into its value very often (in order of hundreds per minute), it can be very exhaustive load for spaceLYnks.

I am copying my modbus handler script here:

-- modbus init

if not mb then

--****************************************************

-->>>>>>>>>Modbus slave setting<<<<<<<<<<<<<<<<<<<<<<<

require('luamodbus')

mb = luamodbus.tcp()

-- IP:10.154.12.78, port: 502

mb:open('10.154.12.78', 502)

mb:connect()

-- slave id

mb:setslave(10)

-- init slave storage for coils, discrete inputs, holding registers and input registers

mb:setmapping(10, 10, 10, 10)

--*****************************************************

-->>>>>>>>>>>Register write callback<<<<<<<<<<<<<<<<<<<

mb:setwriteregistercb(function(register, value)

  if register == 0 then

  grp.write('4/5/1',value)

      elseif register == 1 then

        grp.write('4/5/2',value)

      elseif register == 2 then

        grp.write('4/5/3', value)

      end

alert('register: %d = %d', register, value)

end)

--*****************************************************

end

-- server part init

if not server then

require('rpc')

-- incoming data handler

local handler = function(request)

local fn, res

fn = tostring(request.fn)

if not mb[ fn ] then

return { nil, 'unknown function ' .. fn }

end

if type(request.params) == 'table' then

table.insert(request.params, 1, mb)

res = { mb[ fn ](unpack(request.params)) }

else

res = { mb[ fn ](mb) }

end

return res

end

server = rpc.server('127.0.0.1', 28002, 'mbproxy', handler, 0.01)

end

mb:handleslave()

server:step()

[Koen_Rowies]

Hello Tomas, this script works fine, Thank you!

I have noticed when scanning for modbusdevices with PMC that he recognises multiple devices and not only slave on address 10,

Also when writing to the HL he will save the value even if you put in a different slave address...

Could it be because we are on Modbus/TCP, so the IP address is unique to the slave... and the slave address doesn't matter that much?

[sesa299442]

Koen,

you are right. The slaveid has no function in this case.

The slave device is fully determined by IP address and port number.

Note:

You can use this specification (IP,port+slave ID) in homeLYnk as a master, when you want to connect to Modbus gateway and access the devices behind the gateway.

If you use e.g. Smartlink IP, you can connect to Smartlink via modbus IP and read the the values from Modbus RTU devices(specified by slaveid) connected to Smartlink.

This is the situation when you can use both IP,port specification and slaveid together.