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Convert int16 to float16 - Printable Version

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Convert int16 to float16 - fleeceable - 28.02.2020

Hi!

I'm working on with special modbus script. 
I have Corrigo ventilation controller and communicating over ModbusRTU. When I read register with profile then it is converted automatically thanks to this line:

{ "name": "Outside temp", "bus_datatype": "float16", "datatype": "int16", "type": "inputregister", "address": 0, "value_multiplier": 0.1, "units": "C" },

So this works.

Now I'm going to use scripting. How can I convert integer to float via script?

For example, received value is 65523, it should be -1.x degree.

RE: Convert int16 to float16 - Daniel - 29.02.2020

What is the point of using script when profile work?

RE: Convert int16 to float16 - admin - 02.03.2020

float16 is supported by the modbus mapper. Just use "datatype": "float16" and it will work.

RE: Convert int16 to float16 - fleeceable - 02.03.2020

(29.02.2020, 09:24)Daniel. Wrote: What is the point of using script when profile work?
I have 5 ventilation controllers. There is about 130 modbus points what I need to read per controller. From that, 100 is alarm points. If there is A or B alarm, I will read alarm points also. (A and B alarm is sum of all these) 
And ventilation controller can handle 10 answers per 1 fast request.

So it's quite messed up system on there but I can take control via scripting.
(02.03.2020, 07:42)admin Wrote: float16 is supported by the modbus mapper. Just use "datatype": "float16" and it will work.
Actually this way what I wrote it will work...

Now i'm scripting. I will add screenshot but answer is 65523 with minus degrees. If outside temp is over 0 then it will be correct number.
Also my variable is in 2 byte floating point format but grp.update gives 6552.3 or something like that.

RE: Convert int16 to float16 - Daniel - 02.03.2020

If in profile value_multiplier": 0.1 works then you should do the same here
outside_te*0.1
I don't think the 65523 is a correct value. Usually such is send when No value or no sensor is on PLC side.

RE: Convert int16 to float16 - admin - 02.03.2020

Real datatype is float32 not float16. Correct profile entry should be:
Code:
{ "name": "Outside temp", "bus_datatype": "float32", "datatype": "float32", "type": "inputregister", "address": 0, "units": "C" },


RE: Convert int16 to float16 - fleeceable - 02.03.2020

(02.03.2020, 15:33)Daniel. Wrote: If in profile value_multiplier": 0.1 works then you should do the same here 
outside_te*0.1
I don't think the 65523 is a correct value. Usually such is send when No value or no sensor is on PLC side.
I figured out.

uint16 max value is 65535. If minus degrees, value is changed reversely.

65535-65523=12
12/10=1.2 
1.2*-1=-1.2°C

RE: Convert int16 to float16 - Daniel - 02.03.2020

Try reading it like this
Code:
value = mb:readinputregistervalue(0, "float32", "w")


RE: Convert int16 to float16 - admin - 02.03.2020

I've edited Daniel's example to use internal conversion function. You might have to use different swap parameter (w) depending on your ModBus device. Possible values: n (no swap), w (word swap), b (byte swap), bw (byte and word swap).