#### Topic: Sensor values lower than 0

Hello,

I get values from sensor but sometimes I receive wrong values because they are lower then 0.
I know that the values are wrong becouse it is impossible that fuel consumption was lower than 0.
Could you tell me how can I set each value lower than 0 as equal 0?
I try to do it in calculation table module but without results. Could you tell me what is the formula, please?

Regards,
Martin

Hi, try this:
x:0, a:1, b: 0
X lower bound: 0

flespi

#### Re: Sensor values lower than 0

Hello,

I try this formula but I get all values (positive and negative) as zeros.

#### Re: Sensor values lower than 0

Hi,
what your calculation graph looks like?

#### Re: Sensor values lower than 0

Hello !
I am having the same problem. I want sensor value to be zero for negative values. When custom digital sensor used, I get 1 for negative values,Please suggest

Partner Gurtam

#### Re: Sensor values lower than 0

accrete
in calc table wizard enter the folowing pairs of values:
x = -1, y = 0
x= 0, y = 0
x = 1, y = 1

and click to generate table

#### Re: Sensor values lower than 0

Thanks for the support,I want some more help
I am subtracting constant integer from parameter value and result using as custom digital sensor. I want to ignore negative results and want to work with only two value i.e. 1 and 0
for example : I get parameter values as 233,232,212,211,200 etc. I subtract 232 from parameter and get 1 for 233 and 0 for 232. Other negative results want to be ignored, please suggest

Partner Gurtam

#### Re: Sensor values lower than 0

accrete, use conversion table. e.g. for x < 0, y = 0 and where x > 0 y = 1. Its trivial math:
x a b
-1 0 0
1 0 1

At the dark side of telematics...

#### Re: Sensor values lower than 0

I don't want negative results to be zero instead I want them to be ignored

Partner Gurtam

#### Re: Sensor values lower than 0

accrete, okido, set lower bound as zero in convertation table.

At the dark side of telematics...

#### Re: Sensor values lower than 0

problem not solved yet. I am explaining the requirement in detail. A machine is connected with the device and sending parameter values as 183 means machine turned on,182 means machine turned off. Value 100 comes in same parameter which indicates normal working and this comes after 183 and 182 both every minute. I want to know whether machine is on/off ,please suggest some formula. I tried parameter-const182   but when value 100 comes it does not work. It may be done by using multiple sensors, please help

Partner Gurtam

#### Re: Sensor values lower than 0

You may set calc table:
x a b
182 0 0
183 0 1

and lower/upper values are 182/183. All other values will be ignored. You may also ask same question in Gurtam Help System and our supporter can help you with unit settings.

At the dark side of telematics...

#### Re: Sensor values lower than 0

Hi,

I write because there are too little information in the Wialon User Guide. In the formula y=ax + b
I expect that: Y is the results (sensor values), param a is the angle and there is of course param b.

But the results of the compilation are completely unpredictable for me.

When I write X=0, a = 0, b=0 I get the opposite values. But I expected the whole values as zeros.
When I write x=1, a=-1, b=0 I get multiplied values by 2 and opposite. But I expected receive just opposite values.

So, my question is: How Calculation Table works? Because it doesn’t work as line function: y = ax+b.
Where in this formula are row data from sensor?

Regards,
Martin

#### Re: Sensor values lower than 0

martin, it is y=ax+b on the intervals. You may setup table and see the values on the chart in the next tab.

At the dark side of telematics...

#### Re: Sensor values lower than 0

Ok I used Calculation Chart.

I thought that now the formula is correct.

But I get zero values in the places of plus values.
And I get plus values in the places of minus values.

Regards,
Martin

#### Re: Sensor values lower than 0

martin, images N/A. You may attach them to post.

At the dark side of telematics...

Hello,

#### Re: Sensor values lower than 0

martin,
calc table is proper. Check if you have set any additional options for that sensor like validation.

#### Re: Sensor values lower than 0

Ok thank you,  it works.
Besides formulas in Calculation Table I had formula in Parametr Window: const_value/sensor_value and this formula ought to be in parenthesis.

#### Re: Sensor values lower than 0

shal wrote:

You may set calc table:
x a b
182 0 0
183 0 1

and lower/upper values are 182/183. All other values will be ignored. You may also ask same question in Gurtam Help System and our supporter can help you with unit settings.

I have used the suggested formula. But it is not solving mu problem. When 183 comes it shows ON but when 100 comes after 183  or 182 it shows UNKNOWN.
Please note the sequence how it comes in data. 100 comes every minute indicating normal working
Value  Meaning
100  Normal
100  Normal
183 -- ON
100  Normal
100
100
182  -- OFF
100
100

I want ON )183) to be displayed till OFF (182) comes and vice versa in unit info

Partner Gurtam

#### Re: Sensor values lower than 0

accrete,
please give access to that unit (in PM) or create new ticket in GHS, i want to check settings.

#### Re: Sensor values lower than 0

duig wrote:

accrete,
please give access to that unit (in PM) or create new ticket in GHS, i want to check settings.

Ticket generated in GHS having number 08841

Partner Gurtam

#### Re: Sensor values lower than 0

I was having the same problem, when I used Calculation Chart

#### Re: Sensor values lower than 0

In ticket 8841, X=183 corresponds to ON value, X=182 - to OFF.  The problem was that intermediate value of 100 doesn't allow to uniquely correlate it to one or another state of sensor. It may be solved by creating two notifications of sensor value control type (when X=182 and X=183) and setting options to register different unit statuses.

joannrow
can you clarify it in details?

#### Re: Sensor values lower than 0

Guys wanted to know what type of device you are using, because this happens to certain devices like the Atrack that only sends the info on fuel as a trigger base , and was wondering if anybody had solve this problem. i have asked Atrack to change  the message and include fuel as a parameter, that would be the easiest way to solve