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+--- Thread: modbus - negative values (/showthread.php?tid=5479)
modbus - negative values - Fahd - 21.06.2024
Hi!,
I'm having trouble reading negative values (analog-value , Holding register) from a Modbus device using profiles. Specifically, I'm trying to read a value that should be -10, but I’m getting 65436 from the LM5.
Thanks in advance
{ "name": " Temperature Control Outdoor Air Curve Outdoor Air 1 Setpoint ", "bus_datatype": "float16", "type": "register", "address": 1100,"units": "°C" , "value_multiplier": 0.1, "writable": 1},
RE: modbus - negative values - Daniel - 21.06.2024
Did you try different datatype?
RE: modbus - negative values - admin - 21.06.2024
Default "datatype" is "uint16", you need to add "datatype": "int16" to your profile.
RE: modbus - negative values - Fahd - 21.06.2024
(21.06.2024, 09:57)admin Wrote: Default "datatype" is "uint16", you need to add "datatype": "int16" to your profile.I change it to this (bellow) and still have the same issue
{ "name": " Temperature Control Outdoor Air Curve Outdoor Air 1 Setpoint ", "bus_datatype": "float16", "dataype": "int16" , "type": "register", "address": 1100,"units": "°C" , "value_multiplier": 0.1, "writable": 1},
{ "name": " Temperature Control Outdoor Air Curve Outdoor Air 2 Setpoint ", "bus_datatype": "float16", "dataype": "int16" ,"type": "register", "address": 1101,"units": "°C" , "value_multiplier": 0.1, "writable": 1},
RE: modbus - negative values - Daniel - 21.06.2024
What is documentation saying about this register?
RE: modbus - negative values - admin - 21.06.2024
You have a typo in your profile field: dataype instead of datatype
RE: modbus - negative values - Fahd - 21.06.2024
(21.06.2024, 10:13)Daniel Wrote: What is documentation saying about this register?
Variable_Type : HoldingRegisters
Variable_Index : 1100
Scale : - 1
Data_Type : 16bit signed
Access : R/W
Unit : °C
Range : -300 to 450
(21.06.2024, 10:15)admin Wrote: You have a typo in your profile field: dataype instead of datatype
Thaaanks a lot