Measuring & drawing

hey all,
i've got the siemens step7-200 cpu 222 & the analog to digital extension EM 231 and i've a task to do which is to measure the voltage and current flowing in my local network of electricity and to draw their wave forms which needs very high accuracy as the frequency in the network is 50hz which means that 1 cycle of the voltage wave form takes 20msec. and we need to get all the points within 20 msec. so any help!!!???

just my opinion

You can do it with s7-200 controller, but you will need a display to show the trends. I don't know what will be the exact price for this analyzer base on Siemens controller and display, but I think that you have to search and buy a specialized one (something like this).I think it more reasonable to use electric network analyzer than modifying the controller. Anyway, you have to use transformers to measure the current and voltage if you use s7-200 .... and so on. If you not familiar with such a electrical measurements you better stop here. And on the other hand it's a nosense to user a PLC as an analyzer. It's seems to me like using a PC only as calculator. If you have any questions, ask.

Thank You Bio

thank u very much,
of course i'm not using the plc as an analyzer but that's a part from the task the plc should do to measure the output of an induction machine and hence increases it's speed tht's all

I don't think it's possible

I don't thin it's possible to do it with PLC.
1st. you should convert the sinusoidal wave with 50 HZ to a signal the PLC can deal with i.e. 0/4 to 20 mADC or 0 to 10 VDC.
I know that there are some voltage transducers and current transducers but they just take the RMS value of the AC current or voltage and drive a mA DC or VDC signal.
Sometimes I do this to see the variation of current or voltage all the time through the PLC.
If you could ever ( by any means ) transmit your instantaneous values to the PLC and force the PLC to read it every 2 msec ( I don't think it's possible as you say it's only part of the task ). You will be still facing a big problem which is the HMI.
I don't think that you can get a real time value from the PLC every 1 msec with PPI cable.
The solution as BIO mentioned is to buy a network analyzer to do your job.
You said you want to make a speed control using a PLC.
What type of control you intend to do?
I mean for speed control, it's alwaysa matter of encoders,drives and PLCs.
Why do you need to see the wave form?!
The wave form issue is solved inside the drive and it's never solved inside PLCs.