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+--- Thread: Help with a first knx to modbus (/showthread.php?tid=1272)
Help with a first knx to modbus - stevesu - 03.03.2018
Hi everyone,
i have a project coming up where i have to control a Danfoss novoCom 6 valve trough the modbus interface on a spacelynk, after reading several documents en guides i managed to write the json profile wich i uploaded to the spacelynk (the profile ,if working , i am happy to post it on the forum).
Now the next qeustion i have, if i go throug the manual provided by Schneider i have to make scripts to control the valve or have i misunderstood it, or do i have to link the grp.adres with the percentual value from thermostat to the profile ?
If someone can help me with this i would greatly appreciate it
with regards steven
RE: Help with a first knx to modbus - Daniel - 05.03.2018
Hi
If you add "writable": 1 then any value written to the mapped address will be sent to modbus.
BR
RE: Help with a first knx to modbus - stevesu - 16.03.2018
hi Daniel,
first i want to thank you for the reply but it was really busy the last two weeks with the project.
i managed to write a profile and it works for a part , switching between cooling and heating works but when i want to send a % value to the valve
i get no response from the valve (feedback trough a register or visual by LED's on the valve), first i got errors but then i changed type from "register" to "input register" and the errors are gone but like i said no respons on the valve .
if someone can look into it , i attach the profile and the a piece of the datasheet of the valve into the reply.
i really hope someone can give me a hand with it
greatings steven
RE: Help with a first knx to modbus - Daniel - 16.03.2018
Hi
Input register can be only read. To read and write you have to use holding register.
Try RTU Read test to find correct settings.
BR
RE: Help with a first knx to modbus - stevesu - 16.03.2018
so if i understand well when i set "writeable : true" the type is "register" and if it is "false" then it is "input_register" ?
RE: Help with a first knx to modbus - Daniel - 16.03.2018
https://en.wikipedia.org/wiki/Modbus
RE: Help with a first knx to modbus - stevesu - 17.03.2018
so if i use following for writing to register 33280 , witch have functioncode 3,4 & 16 (datasheet)
Code:
{ "name": "Flow Rate Setpoint", "bus_datatype": "05", "type": "register", "address":33280, "writable": true , "value_delta": "0", "datatype": "float16" },Code:
{ "name": "Actual Flow Rate", "bus_datatype": "05", "type": "inputregister", "address":33282, "writable": 0, "value_delta": "0" , "datatype": "float16" },ps: when i read "register" i must actually read "holding register".
sorry for asking these qeustions, but it is all new for me and having someone to explane it makes it a bit easier
RE: Help with a first knx to modbus - Daniel - 17.03.2018
You can use register for reead and write.
Use RTU read test to find correct settings. Most likely modbus dpt is nof float only int16