Two’s complement math eliminates the end
around carry of the Sign-Magnitude method,
which uses only one complement math, and
the two forms of Sign-Magnitude zero are
reduced to only one zero.

As always, I could be wrong.

1111 1111 (-1)
1111 1111 (-1)
==== ==== +
1111 1110 (-2)

0000 0010 (+2)
1111 1111
==== ==== XOR
1111 1101 (-3) Ones Complement
0000 0001 (+1)
==== ==== +
1111 1110 (-2) Twos Complement

0000 0001 (+1)
1111 1111
==== ==== XOR
1111 1110 (-2) Ones Complement
0000 0001 (+1)
==== ==== +
1111 1111 (-1) Twos Complement

0000 0000 (0)
1111 1111
==== ==== XOR
1111 1111 (-1) Ones Complement
0000 0001 (+1)
==== ==== +
0000 0000 (0) Twos Complement

The long list of data was provided as a
way to determine correct slope of the
equation by slowly twisting the distributor until
a P1345 DTC is triggered then comparing
its raw hex response at a known degree
against the posted equations.

I believe the latter equations are more likely
to be accurate. (Confirmed).

https://en.m.wikipedia.org/wiki/Two%27s_complement

Edited.

I’ve been trying to access the CMP on my 2000 K3500 7.4L using a Kobra bluetooth adapter with no success so far.

Car Gauge Pro couldn’t connect using the GM powertrain option (failed to connect to ECU). It connected fine using the generic OBDII setting but then I don’t have access to the GM extended PIDs.

I purchased Torque Pro and made a custom PID for the CMP per the instructions here. It just displays a “-” in the digital gauge readout. About 1/4 of the PIDs are green when I add a gauge – I’m assuming that means those PIDs are available since they have readings when I add them. None of the PIDs proceeded with [GM] are green or have readouts.

I installed the trial version of Dash Command and tried to follow the instructions posted by DCS to see if I have access to CMP but I don’t the little 3-dot menu button at the bottom right. But there are no GM specific PIDs in the PIDs available to me.

I figure either the Kobra adapter isn’t allowing access to the GM extended PIDs or the protocol is different on a 2000 K3500 (GM did make both the K3500 and the 1 ton Silverado that year). Which is more likely? I’m willing to either buy a different bluetooth adapter (BAFX) or Dash Command if that will solve the problem.

Thanks

yes, it works, I just checked it for you
2a
6a 09 00 ff 34 56 78 65
R3 = 255

https://yadi.sk/i/k-fvQlIoSl5SEA

R3 = A = N0

R2 = 0
R3 = 255
N0 = 255
A = 255

I understand that in the program for query 2A, the header in the response is taken conditionally as 3 bytes

Quote from cintakc on March 3, 2019
Capp777, Can I ask you a question
Can you tell me the solution to this problem, one person really needs it,
you need to fix on the device let’s say the maximum speed, that is, the speed rises for example to 67 km / h, then the speed starts to decrease, and the fixed maximum value of 67 km / h remains on the device

End Quote.

Are you saying the display is not following
the decreasing speed?

or the user is trying to lock the display at the
maximum value?

Assuming the max value was set by long
pressing display…then display config…
Set max value.

Trying to recreate…

Using a dial needle display and using
equation random()*75…

The max value within the pid editor gives
a starting range that will change with larger
values.

Setting max from display config will lock
display needle from exceeding its setting
but the needle did follow decreasing values
afterwards.

—

Changing same display to digital shows
values changing above and below max
settings. Even after exceeding max setting
values decreased properly.

So far have not been able to recreate issue.

—

For comparison function I have been testing
something like…

lookup(Val{Scaled MAP Factor}::0=A:1~2550=A*(Val{Scaled MAP Factor}/255))

where variable A is from [0b] pid and factor
is from another pid.

If Factor = 0 then
…Equation = A
else
…Equation = A*(Factor/255)
Endif

Edited.

https://torque-bhp.com/forums/?wpforumaction=viewtopic&t=11951.0

Edited again for min/max equation examples.

Thank you, we also could not find a solution, it is a pity that there are no comparison operations in the program

Capp777, thank.

Quote from RKCRLR on December 4, 2018
I’ve been trying to access the CMP on my 2000 K3500 7.4L using a Kobra bluetooth adapter with no success so far.

Car Gauge Pro couldn’t connect using the GM powertrain option (failed to connect to ECU). It connected fine using the generic OBDII setting but then I don’t have access to the GM extended PIDs.

I purchased Torque Pro and made a custom PID for the CMP per the instructions here. It just displays a “-” in the digital gauge readout. About 1/4 of the PIDs are green when I add a gauge – I’m assuming that means those PIDs are available since they have readings when I add them. None of the PIDs proceeded with [GM] are green or have readouts.

I installed the trial version of Dash Command and tried to follow the instructions posted by DCS to see if I have access to CMP but I don’t the little 3-dot menu button at the bottom right. But there are no GM specific PIDs in the PIDs available to me.

I figure either the Kobra adapter isn’t allowing access to the GM extended PIDs or the protocol is different on a 2000 K3500 (GM did make both the K3500 and the 1 ton Silverado that year). Which is more likely? I’m willing to either buy a different bluetooth adapter (BAFX) or Dash Command if that will solve the problem.

Thanks

I thought I’d post a followup for anyone else struggling with this.
I purchased a OBDLink MX+ adapter during a Black Friday sale.
I got the custom PID for CMP to work. I had to change the OBD Header to auto. I tried switching back to the Kobra adapter to see if it would work – It doesn’t.
I had checked my CMP with a borrowed professional scanner. It was around -1.8 degrees. I got around -0.7 degrees when I checked using Torque. I found a post on another forum where the user had similar results. He changed the factor from *0.024 to *0.063 to get results from Torque and Gar Gauge Pro to match. I get around -1.8 degrees when using *0.063 so I’m going to use that.