Analogue function: S7-200

[xraytek]

Hi guys,
I have no experience with analogue outputs on PLC's, so was hoping someone can confirm or correct the following requirement:

I have a 0-10v scaled input going into my PLC and want that input to be duplicated on one of the analogue outputs.

Is it just a simple case of using MOV-W (move word) with AIW0 going in and AQW0 going out, or do I have to move the word to a memory location and then read from that, or something else completely different?

I have had a look in the manual regarding analogue I/O and can see how you can provide set outputs but not variable ones based on an input.

Thanks in advance.

 

[Darkwood]

Not familiar with the plc you use but if your starting up i find the 'siemens logo' very easy to follow and can all be run virtually on the laptop long before you ever connect anything, so you can fiddle and run your programme till your hearts content and then hard wire it after.
I assume your using a laptop to change and alter the logic functions as using the built in LCD and front panel buttons is tedious and mind numbingly fiddley on some models.

 

[jpmiff]

hi,
we use allan bradley plc's at work.

you should have a register of all your program and controller tags in your plc program,
find the analog input tag,this may be tagged as "raw in" which is the number of bits aquivelent to your 0-10v in, also note the scaling tags,
create an analog output tag, you can enter your scaling for this analog out put tag in here.
use a move function to move the analog "raw in" to the analog out tag.
if all the output scaling settings are the same as the input settings the analog output will be as the analog input.

 

[pmac10]

what brand of plc are you using?

 

[xraytek]

Thanks for the replies.
Hi pmac10, the PLC is a Siemens S7-200 and is programmed using Step 7 Microwin.

Hi jpmiff, I will have a look for that type of tag on monday but dont recall there being any analogue tags. The S7-200 appears to convert the input to a 16 bit word length which is why I am thinking that I use the move word function to move an input straight to an output.

Hi darkwood, I am new to PLC programming but must use the s7-200 for my project. The programming is via a laptop and RS485 lead, and fortunately seems to be quite user friendly.

 

[pmac10]

hi mate. of the top of my head siemens s7 analogue inputs are assigned as variable word memory, like IF AIW11 for analogue input word 11 THEN MOV whatever to ENABLE out VB5 for variable bit word 5, think you need to write these locations as analogue input/output, the HELP button on S7 will be able to point you in the right direction, i,m not a big fan of S7 although it is excellent software, if you have the opportunity, mitubishi gx developer is a good program, you have special instructions which define analogue input/output end of, saying that, plc programming software is as good as the programmer feels familiar with it.
if you need further assistance give me a shout, i have S7 on this laptop

 

[pmac10]

just reread your original post and think your spot on with what youre doing, sorry for waffling on!

 

[xraytek]

just reread your original post and think your spot on with what youre doing, sorry for waffling on!

Dont apologise, its all good stuff!
Thanks

 

[jpmiff]

how have you got on?

 

[xraytek]

how have you got on?

I should know by the end of this week and will let you know either way mate

 

[xraytek]

Just to let you know, I have now been able to try out the analogue output and all is working fine.
I was able to use 'move-word' to move the input straight to outputs without the need for moving to variable memory first.

 

[pmac10]

thanks for the update xraytek

 

[jpmiff]

Hi,
thanks for the update, happy its working ok