LM5 Modbus TCP

[OysteinEl]

Hi
Im about to setup a LM5 as a modbus gateway, but i am having issues with how to setup the socket.

I have tried setting up a socket in a script as:

1. 2. if not mb then
      
      
   3.     require('luamodbus')
      
      
   4.     mb = luamodbus.tcp()
      
      
   5.     mb:open('192.168.250.5', 10502)
      
      
   6.     mb:connect()
      
      
   7. end
      
2. The 192.168.250.5 are the modbus slave(server). But it does not connect. 

 

I have also tried setting it in the Modbus tab

Any ideas ?

[admin]

Check if you can ping the device from LM. Go to System config > Status > Network utilities > Ping.
Are both devices on the same sub-network?

[OysteinEl]

The ping works fine, the ipconfig are as following:

LM5: 192.168.250.10
255.255.255.0

Modbus Slave: 192.168.250.5
255.255.255.0

they are both on the same switch so there should not be any closed ports.

[admin]

Are you sure about port 10502? Default modbus port is 502.

[OysteinEl]

Im testing it towards a Node-Red slave right now, and they are fuzzy about the 502 port (admin/root control) Both the LM5 and the Node-red slave are setup with 10502. I have got the 10502 and Node-red working with other equipment.

I have tried moving them to a 502 port, and there are the same issue, it does not seem to connect.

[admin]

You can log the connect() call result in your script:

Code:

require('luamodbus')
mb = luamodbus.tcp()
mb:open('192.168.250.5', 10502)
res, err = mb:connect()
log(res, err)

You will probably get "Connection refused" which means that the remote host is alive but the requested port is not available.

[OysteinEl]

Port 502:



Running the script i get this:

---

deactivating the script and Running the modbus setup:

---

In the Error Log:

Test (TCP 192.168.250.5:502) connect failed: Operation in progress

[admin]

Try connecting by using socket library and post the results. Try both port 10502 and 502.

Code:

sock = require('socket').tcp()
sock:settimeout(5)
ts, tu = os.microtime()
res, err = sock:connect('192.168.250.5', 10502)
log(res, err, os.udifftime(ts, tu))

[OysteinEl]

Top one are 502, bottom are 10502

[OysteinEl]

I see now that the LM5 are being setup as a Modbus Slave, opposite of what the manual states. I have started a Modbus Master instance in Node-Red that receives data.

'Modbus Master – user graphical mapper interface in Modbus tab
Modbus Slave – to use LM as Modbus Slave, disable Modbus RTU in Modbus→RTU settings,
and use scripts for the communication'

is there anyway to change this ?

[admin]

The only limitation is that you cannot use both master and slave on the same RTU port. This does not apply to TCP.

[OysteinEl]

How do i get the LM5 to act as an modbus tcp master ?

another question i get data from the Node-Red system now but the knx will not react to it:



I see that the 'Current Value' changes and works fine when:
- Operating the light switch  KNX->LM5 
- 'Set value' function LM5->KNX

but this one does not send from LM5->KNX
- Sending true or false commandos from Node-red  Node-red->LM5->KNX

this does not send to the knx bus, the statusline above was changed from Node-red but the knx bus does not turn on or off the light.
 any ideas, no filters are applied.

[admin]

For modbus master you can either use mapper by creating a JSON profile for the slave device or use scripts for the communication.
As for writing not working check the hop count value in the telegram.

[OysteinEl]

For modbus master you can either use mapper by creating a JSON profile for the slave device or use scripts for the communication.
As for writing not working check the hop count value in the telegram.

{
  "manufacturer": "Test",
  "description": "Test",
  "mapping": [
    { "name": "Output 1", "bus_datatype": "bool", "type": "coil", "address": 0, "writable": 1, "write_only": 0 },
{ "name": "Output 2", "bus_datatype": "bool", "type": "register", "address": 0, "writable": 1, "write_only": 0 }

  ]
 
}
That is what i have been trying, i have a script, it works when Node-Red are the Master and LM5 act as a slave. 



I have tried using the LM5 IP address to point to itself, but it gets a connection refused. As it does not setup a Master device in it self. I can only get the LM5 to act as a slave device.

[admin]

Modbus mapper UI is Master. Modbus Slave can be done only via a script at the moment. If the script is running then check if ports are the same in the Modbus device UI and the script.