hello......,

i'am trying to wire a 'citec 10 k potentiometer'  to my cpu 1212c. in the attachement you can see the 3 connectors with which i'am doubting to use.  with programming i dare to try a lot but with this kind of stuff i'am a little bit affraid to damage the analog card or something else. i created a move instruction in a function,  moved iw64 to mw 64.  only just to monitor what the analog input would do but it was '0000'  or 6FFF but it isn't variable.

i'am convinced that it must be possible to connect a potentiometer to my plc. does anyone has tips how to do it

gr gerard 

Hi.

You need 0V to 10V on the analog pins.
The trouble is that you do not have 10V supply - like you may have on a VSD / motor drive.

One suggestion would be the voltage divider seen in the attached image.

Greetings.
w

william,

it took some time because i needed to order some resistors, but now it works.  i didn't manage it to get exactly 14k but with 10k  it also works but the scaling is a little bit different.  and that for just 0.15 euro. it's amazing.  but  how can i explain that if i disconnect the wire from my potentiometer to the '2m'  of the plc, the plc starts to error. 

and also in my project i am trying to fine-tune some things with counters and timers. but every time if i change a 'pv'  value from a timer or a counter and i upload it.  i need to stop the plc and put it back to run again before the new value is,   how do i say it,,   active .   it must also be possible to change pv values and stuff,, in the mean time while the plc keeps running

gr gerard

hello...........,

i'am trying to scale my analog input back to a value so that i can use it as a 'pv' input for my counter. in the attachement you can see my progress so far.  A= scale of analog input,  B = scale that i want. C= output that i want, but this '5' is correct  but only because i right mouse clicked on it and modified the display format to floating point.  but if i use 'registrovast' as an input for my pv in my counter it doesn't work

so in network 3 i tried some move/ convert instruction to get the '5' useable for input pv in my counter but i don't get it exactly right. what do i do wrong 

gr gerard

gerard32

hello............,

still i am trying to scale the value of my potentiometer so that i can use it for a counter. (issue above)

but i haven't got any reaction.   ,is it unpossible or strange question.

if you don't know, perhaps... tips..

gr gerard

Have you tried the "SCALE_X (Scale) and NORM_X (Normalize) instructions"?

Joshua H.

gerard32

hello............,

still i am trying to scale the value of my potentiometer so that i can use it for a counter. (issue above)

but i haven't got any reaction.   ,is it unpossible or strange question.

if you don't know, perhaps... tips..

gr gerard

 

Have you tried the "SCALE_X (Scale) and NORM_X (Normalize) instructions"?

Joshua - would you mind giving our friend an example to work from.
A screen capture would do nicely.
Thanks.
w

hello..............,

a screenshot or example would be nice now i'am doing a lot with scaling and conversion. but not in the way i want 

gr gerard

hello...........,

that scaling thing is working now, thanks

i created "level_1_norm"  and "level_1_norm1"  as an temporarly variable.  but how is it possible that when i load the program into plcsim and monitor these values while using the potentiometer the values remain 0 while the rest of the program is working as it supposed to be. i can not monitor the values

 i also used the round function to get a number without decimals. 0-100

perhaps its difficult to explain what i want.  but once i saw an scada aplication in which they used what i use as "#level_scaled" (0-100).  to other values. now 0 to 100 is linear. but what if i want exponential how does that works in siemens.

or more complicated lets say 0-100 is X and i want for every individual X value an specified Y value. like in a table, for example  X2= 5   X3=10  X4=14  X5=19   X6=22.  i managed to get what i want with a lot of comperators and stuff,  but is it also possible to create an table

gr gerard

hello...........,

i haven't had any reaction yet,  anyone an idea why that is

gr gerard

hey huggy,

in the attachement i created an array but why do i need to do it with UDT i managed to do it without,   the floating point was not an option so i choose word because the output of the trunc function is also word.  but now the next  step. 

the trunc function creates a 6 but with this 6 i want to have eventually the 22 in the circle, but how do i do this what function do i need to use 

gr gerard

hello.........,

whatever i try. i don't get this thing to work,  if anyone has tips or an example 

please let me know

gr gerard 

William_B

Hi.

You need 0V to 10V on the analog pins.
The trouble is that you do not have 10V supply - like you may have on a VSD / motor drive.

One suggestion would be the voltage divider seen in the attached image.

Greetings.
w

 Hi William its me again :). I  use connection like you show us in picture but i use 100K and 140K resistor. My problem is when I connect it to AI0 and 2M voltage decrease from 9.9 V to 6.2 V. So it means that i can control voltage by potentiometer from 0V to 6.2 V but I dont know why... when I disconnect cable from AI0 and 2M I control voltage from 0V to 9.9V again....

I use internal 24VDC from PLC S7-1200.