WHat controller to use

misslead

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• Jan 19, 2012

• #1

Hey people

I am struggling at the moment to find the correct controller to use.
I have an S7-300 at my disposal but i feel it is over engineered for my needs.

I am creating a small project which will only utilise three DI's, two DO's and one 0-20mA AI.
I also have a small siemens logo unit but unfortunately i can not see a 0-20mA AI.

Can anybody recomned a more suitable controller i could use please. I would be very greatful.Unfortunately I would like to keep it a siemens product.

Thank you for your time​

 

nehpets

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• Jan 19, 2012

• #2

you could try using a CM EIB/KNX communication module for the logo
I don't know too much about Siemens so you may have to google it

Steve

 

Hietsu

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• Jan 19, 2012

• #3

Logo! Basic module has four analog inputs itself, so you don't need expansion modules for it.

Inputs I7, I8, I1 and I2 can be used either as digital or analog inputs(at least in version 0Ba6).

 

misslead

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• Jan 19, 2012

• #4

Thank you

Thank you for your responses.

I did realise the logo unit had AI's but i thought they were only 0-10V and I need 4-20mA, I could convert the current change into a voltage change via a resistor i guess but that would involve a PCB etc which i was trying to avoid.

Thanks anyway i will look into the logo unit and see what i can do.

 

JesperMP

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• Jan 19, 2012

• #5

Consider the IM151-8 CPU with ET200S i/o.
Much cheaper than a similar S7-300 configuration, if not nearly as cheap as a logo or an S7-1200. The advantage is that you program it exactly as an S7-300, so it will be straightforward for you. Dont underestimate the time and expense for learning a different PLC.

 

Clay B.

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• Jan 19, 2012

• #6

Small Job Small PLC

Take a look at these http://www.unitronics.com/Series.aspx?page=Jazz

We use them for small jobs similar to what you are talking abut. The PLC is $200 or less US and the programming software is a free download from the internet. They have a model that has 2 Analog In and 18 discrete in with 20 discrete out.
You will need to purchase a programming cable separate but it is also less that $100 US.

I think we are over 60 in the field with no issues. We have had one fail out of the box since we started using them so I feel confident recommending them.

 

TurpoUrpo

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• Jan 19, 2012

• #7

S7-1200 is not that different from S7-300 (from programming pov).

 

danw

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• Jan 19, 2012

• #8

>I could convert the current change into a voltage change via a resistor i guess but that would involve a PCB

Wire the resistor leads across the two analog input terminal, one lead to the (+) terminal, one lead to the (-) terminal.

Some people crimp a spade lug to each resistor lead.

No PCB needed.

 

brucechase

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• Jan 19, 2012

• #9

I know you said Siemens, but I've used the new AB Micro810 8 inputs (last 4 can be digital or analog in) and 4 outputs. Programming software is free and I learned it in about 2 hours. Cost is in the $80-$90 range.