2.8.10546 OEM Release
PV780
WIN 10 PRO

I had a customer tell me about a situation that his people are noticing in the operation. The PV780 is used in a moving application where they are driving the machine. The situation described is that sometimes when the operator presses on the throttle pedal, the text gauge would go up to 100% and gray out (go invalid).

I started looking into the configuration and running some tests. The Accelerator Pedal Position 1 (PGN 61443 SPN 91) is the J1939 parameter being displayed. The variable is allowed to go invalid after 5 seconds (set up in the Programming tab).

The minimum and maximum values displayed are set to 0 and 100 on the text gauge properties field as shown in the image below:
On the Library tab in PowerVision, looking at the J1939/NMEA Parameters section, on the bottom right corner when highlighting the PGN, there are two fields Min Value and Max Value. I had these set to 0 and 100 respectively.
This particular parameter is packed into a single byte of data so the raw value in the message can be between 0 and 255. Because the scaling factor is 0.4 and the offset is 0, a raw value of 250 would represent a scaled value of 100 [%]. With the set up as shown above, and a CANCapture transmission of 250 in that data byte, the displayed value will gray out and go invalid after 5 seconds. A value of 249 equates to 99.6 and would round up to display 100% on the screen.

A raw value of 255 would be a scaled value of 102. I changed the Max Value in the Parameters section to 102 and sent a 255 and the display showed it as invalid. Sending a 254 would show not invalidate it. I had to make it a 103 in the Max Value in order to not go invalid.

It seems like the invalid check is comparing the scaled value to the Max Value and calling it invalid when it is greater than or equal to the Max Value, rather that just greater than the Max Value. With the set up of 0-100%, a message value of 250 should not invalidate it, but a message of 251 should. I think this is a bug. Any comments on this?

Thank you,

Jacob

This has come up before and it is something that has been in PowerVision for a long time. Like you found the Max Value can be increased by a little to allow the full range. I tested and a Max Value of 100.2 also worked very good. It could be caused by rounding floating point numbers.