Analogue input to a s7-200

I am new to programming an Analogue input and output to a s7-200. Can anyone give me an idea of where to start?



The input will be a 0-20 mA

Output either 0-10V or 0-20mA



Sketch, point in the right direction, help files, any help would be great.

Try the S7-200 Programming manual? Analog inputs come in as input words, and are a numeric value representing the scale of the input. Analog outputs are output words, which will be assigned a value to indicate the output voltage desired. AIW and AQW and addressing expansion blocks are described in Chapter 4.

Hi Bridon:

The first, you have to do the electrical connections properly. You have to configure all the inputs of a card in the same way (in this case 0-20 mA). For example, using a EM231:



And you have to set the microswitches at the bottom of the card like this:



For outputs it is easier, you only have to connect them in the right way to select voltage or current output. For example, using a EM232:



Addressing:

Starting from left to right, only matters the relative position: AIW0, AIW2, AIW4...

It's the same for outputs: AQW0, AQW2, AQW4... and they are independent of the inputs.

Processing the Value:

If you capture the value from the input AIWn, you will get a INTEGER VALUE from 0 to 32000. 0 for 0 mA, 32000 for 20 mA.

You have to do a mathematical conversion to obtain the real value you are measuring. For example, if your sensor gives you 0 mA at 20ºC and 20 mA at 60ºC, you have to:

• Convert the INT value to REAL
• Divide it by 800 ( because 32000/(60-20) = 800 )
• Add 20 (because 0mA --> 20ºC)

Yo may calculate it easier using a function from Nubitek Free Utils. It helps the programmer to obtain the real value from the analog sensor.
http://www.nubitek.com/section02/pr10-free_utils.htm



You have to do the opposite proccess for analog outputs. You want to get a reponse as a real value range at your external device, so you have to write a value between 0 and 32000 in the AQWn field.

Good luck with that!

Regards,

Lorenzo Rivas
www.nubitek.com

if its not to late. maybe i can help you, but you need to send me your e- mail. i have already creaded analog bloks ([email protected])