Putting a signal value into a variable in CAPL

Question

I am trying to pull a signal value (from a DBC file) into a variable but I get the message "Must be constant expression". If I try adding a filter like .DefaultValue, it works but that isn't the value I want. I want the value of the signal at the time of me calling this CAPL function. Here is an example:

float Cell_Voltage = Mc00_UCell00; (this is where I get error of must be constant expression)

float Cell_Voltage = Mc00_UCell00.DefaultValue; (this works but I don't want the default value)

Is there a filter to pull the current value of the signal Mc00_UCell0?

@toohones Please explain you tag editing. It does seem like C to me. — Yunnosch, Sep 07 '18 at 16:04
@Yunnosch: CAPL is not C, but a DSL for a CAN bus analyzer, read the question carefully and see the tag descriptions. It might share some syntax with C, nevertheless it is not. (and how do you think you can tell it's C from those two lines, could be Java, C#, C++ and some dozens other languages. — too honest for this site, Sep 07 '18 at 16:06
@toohonestforthissite Thanks. It seems you knew what you did. — Yunnosch, Sep 07 '18 at 16:13
@Yunnosch: I generally try to, even if I don't always see reason to explain every detail:-) — too honest for this site, Sep 07 '18 at 16:33

score 1 · Answer 1 · answered Nov 01 '18 at 05:55

1

In CAPL to get integer of float signal value you should write

float Cell_Voltage = $Mc00_UCell00;

It is called "Direct access to signal values"

answered Nov 01 '18 at 05:55

Anton Salnikov

31
3

score 0 · Answer 2 · answered Sep 07 '18 at 16:13

You say the following works:

float Cell_Voltage = Mc00_UCell00.DefaultValue;

and the following doesn't work:

float Cell_Voltage = Mc00_UCell00;

Note that in C and many other languages, a dot indicates that from a structure a member is accessed. That would mean that in the working example you access a member and assign that to Cell_Voltage and in the not-working example you want to assign a whole strucure to a simple variable, and that indeed won't work.

Decide which member of the structure you need, and address that with the dot notation.

Putting a signal value into a variable in CAPL

2 Answers2