Calculation event does not work

T Takehara · Post by **T Takehara** » Tue May 10, 2016 5:04 am

Hello,

Our customer added a calculation event "average fuel rate" and put the following expression on that event to calculate the average fuel rate from total fuel used and engine total hours. Both parameters are sent via J1939 and they confirmed that both parameters were displayed on the monitor correctly, but the calculation event remained 0.

Exoression
[J1939_Engine_Total_Fuel_Used/J1939_Engine_Engine_Total_Hours_of_Operation]

Please find the attached picture and could you advise if there is any wrong in the configuration?

Best regards,

Toshiki

stalley · Post by **stalley** » Tue May 10, 2016 6:44 am

Hello Toshiki,

Look at the properties of the text gauge used to display the Average Fuel Rate. If it only displays integers and the result of the calculation event is less than one, the gauge will show zero. It is best to have the gauge show one or two decimal places and change the Smallest Increment property to 0.01.

If your customers try this and the result of the calculation event still results in 0, please let me know what version of PowerVision Configuration Studio they are using.

Best Regards,

T Takehara · Post by **T Takehara** » Thu May 12, 2016 2:04 am

Hello,

The result of calculation event is more than one because the numerator of total fuel used is larger than denominator of total hours (I.e. 1087 L/60.47 h = 17.98 l/h). They also set the decimal places as 1 (0.0 l/h).

The version of PowerVision they use is 2.7.10475 but their configuration was originally created by version 2.2 or 2.3.
That configuration was upgraded many times according to the latest version then.

It is appreciated if you advise how to make a calculation event with CAN data.

Best regards,

Toshiki

stalley · Post by **stalley** » Thu May 12, 2016 8:15 am

Hello Toshiki,

The calculation event looks ok. How or when is the calculation event fired?

T Takehara · Post by **T Takehara** » Tue May 17, 2016 4:42 am

Hello,

The customer wants to fire the calculation event whenever the "total fuel used" and the "total hours" are sent from ECU via CAN.
Both CAN data are correctly sent to the PV780 and are displayed on the monitor.

They tried to uncheck the checkbox of "Fire on change" but it still does not work.

Do you have any idea what the possible causes are?

Best regards,

Toshiki

stalley · Post by **stalley** » Tue May 17, 2016 9:03 am

Hello Toshiki,

I am sending a simple example config that is my recommendation for how to accomplish getting the average value to display. You can't use the on change in this situation.

The variable, timer event and activity program are in the ~Demo group. Variables are displayed on the screen.

The timer event causes the activity program, Calculate Average, to be run every 500msec.
The calculation should only be executed when the fuel and engine hours parameters are being received, that is the AND(ISVALID(),ISVALID()) decision in the activity program.
If the average is not being calculated, the variable is set to 0 to indicate it is not being updated.

This is just one way it could be done, since I am not familiar with the system, your customer may need to do something different.

Calculation event does not work

Calculation event does not work

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