Math problem I'm too stupid to solve

[Indiana_Jones]

-Indy

[jono035]

-Indy

Quit loitering, you're making the place look untidy!

[avgas]

2) use the highest signal levels possible. There is a reason most of the analogue SCADA stuff is done 0-10V

Ha i wish.
4-20mA seems to be common, as does 0-10v then there is PT100 and a few hundred others.
Then you have to chop and change them through the 100's of stupid protocols.

Make the IT world seem like a piece of piss after the BS in SCADA.

[DMCD]

Mind block or something, help me out here.


range one = 0 to 65,536
range two = -150 to +150
value in range one (35325) = what value in range two?


Steps needed to work this out? they told me I needed pay attention in maths if I wanted to work in computers... I didn't believe them :S

I'm useless at maths and I run your internets

Take that any way you wish

[Foxzee]

I'm useless at maths and I run your internets

Take that any way you wish

HAHA...I've taken it the wrong way....LOL

[jono035]

Ha i wish.
4-20mA seems to be common, as does 0-10v then there is PT100 and a few hundred others.
Then you have to chop and change them through the 100's of stupid protocols.

Make the IT world seem like a piece of piss after the BS in SCADA.

4-20mA is really good for longer runs because it is a low impedance signal therefore is relatively immune to most noise sources. Being able to take power from the comms loop is also pretty useful, makes it much easier to have isolated comms or self-powered sensors. It also inherently provides fault detection (current less than 4mA = fault).
The downside is that everything is much more expensive with it and you really have to run everything as balanced loops rather than a bunch of single ended signals and a ground (for slow stuff). You also have to be quite careful when it comes to cable resistance or it can be easy to run into signal clipping issues.

[Skyryder]

First range would make more sense if it was 0 to 65535 (FFFF hex), ie, 65536 distinct values. I'd assume that that's just an error in the form of the question.

Assuming you have no other information than that brain-dead question form, presumably written by someone who was too stupid to get a real job and has therefore ended up teaching, I'd expect that you're supposed to be using an unsigned 16-bit number to represent a range of -150 to 150 decimal.

Which means that you divide 301 decimal (the number of values in your represented range) by 65536 decimal (the number of values in your 16-bit integer) and then multiply the result by 35325 and add the result to your minimum value.

In other words, 12.24.

But, really, I wouldn't have a clue what I'm on about here. Pay no attention to anything I write.

(Edited 302 to 301. See, I told you I had no clue. And edited the result to be added to -150, etc. This whole thread is stupid.)

Well it looks good.

Skyryder

[jono035]

Well it looks good.

Skyryder

Yeah, looks good but unfortunately is wrong

You have to divide by 300, it isn't integer mathematics...

[LBD]

Mind block or something, help me out here.


range one = 0 to 65,536
range two = -150 to +150
value in range one (35325) = what value in range two?


Steps needed to work this out? they told me I needed pay attention in maths if I wanted to work in computers... I didn't believe them :S

35325/65536=0.5390167

150 - (-150) or 150 + 150 = 300

0.5390167 x 300 = 161.70501

161.70501 - 150 = 11.70501