(Siemens S7-300) Choosing the right PLC for the job

[Dariusch]

Hi all,

I have to make a little project including some DI, DO and AI.
The PLC must be a S7-300 serie and have to include a panel also

I need about 30 DI +/-4, 12 +/-4 DO and 7AI (11-12bit).
The project is for controlling waterflow, based on UV-intencity.
It is not a fast application (scantime >100ms is ok).
I would like to go online without disconnecting the panel (2 ports? or DP?)
have 230VAC or 24VDC for supply and 24VDC for transmitteres etc.

I was thinking of CPU 313C-2 (ptp or DP) do not know what is best, + 32DI + 16DO + 8AI
or else
CPU 314C-2 (ptp or dp) + 16DI + 16DO + 8AI

I do not know what panel to use either.

Can someone help me in the right direction?!

Thank you

Dariusch

 

[Doug_Adam]

You would need MPI to program this.
If you are using a siemens panel, such as a TP177 for example, this can communicate on either MPI or DP. MPI is multipoint, so there is no problem using it for communications between the PLC and Panel, as well as for programming the PLC and Panel, and you do not have to disconnect anything. I use this setup often. The only disruption you may cause is when downloading to the panel, you cannot use the panel.

By the sound of it, any S7-300 would be good for what you want.

My company has standardised on the 315 2DP, and the newest one is extremely fast. I bench tested it and it could scan 10,000 floating point multiplication blocks, in ladder, with a scan time of 165-170 ms. (The old 315 2DP took 690ms for the same operation).

 

[seppoalanen]

Doug,

I agree, 315 2DP is only 10 times slower than fe. Omron CJ1M.

Dariusch,

You will need some ProTool or WinCC Flex software for OP-panel engineering. You can use MPI and 2'nd gate could be Profibus-DP, so if you find equipment for Profibus, you don't need Analog I/O.

 

[JesperMP]

If the application is exactly as you have described it, then a 313C with the onboard i/o but without PtP or DP could fit perfectly.
As others have said, with MPI you can go online without removing the panel.

However, you could also consider a setup with a CPU without onboard i/o and then add i/o modules as needed. This is a better strategy if you have several projects and you may have to adjust for smaller or bigger than a 313C.
In that way you need only a limited number of spare parts.
The application sounds like even a 312 CPU would be enough.

 

[girevik]

As others have said, with MPI you can go online without removing the panel.

what kind of cable do you use then?

thanks

 

[JesperMP]

You need a cable made up of two Profibus connectors and a Profibus cable between them.

The connector on the CPU side should be the 6ES7 972-0BB41-0XA0. It has a PG socket built in. So you connect your online cable to the PG socket on the connector.

The connector on the panel side should be 6GK1 500-0FC00.

If you worry about the expense of two Profibus connectors, then consider to normally use the regular, cheap (grey) cable between the CPU and the panel.
When the need arises for going online, you temporarily install the cable with the two Profibus connectors.

 

[Dariusch]

Thank you all for the replies.

You need a cable made up of two Profibus connectors and a Profibus cable between them.

The connector on the CPU side should be the 6ES7 972-0BB41-0XA0. It has a PG socket built in. So you connect your online cable to the PG socket on the connector.

The connector on the panel side should be 6GK1 500-0FC00.

Ok that was the answer for my next question.

Thank you all

Dariusch

 

[girevik]

Thank you for your reply!

So I just need to buy two connectors you have mentioned, + profibus cable (RS485 cable) for example 6XV1830-0EH10 and use my existing mpi cable for connection between plc and pc, and that's all, I will be able to connect tp270 to the plc(s7-314) (through mpi) and plc to the pc (through mpi) at the same time, is that right?

thanks.

 

[Dariusch]

Just one question left.


If the customer maby want to have this CPU on the profibus, after ½ year or so. Can you get a profibus card for the system or should I considder it and choose a CPU with PD on?


Thank you

Dariusch

 

[JesperMP]

You have both options.

You can install a Profibus CP later on.
Or you can choose a CPU with onboard DP port now.

NOTE: The 313C with DP or PtP port have fever onboard i/o than the regular 313C !!! No onboard analog i/o for example !!!

 

[ivo.maenen]

I must say that a S7-300-2DP is more easier to work with then if you have a S7-300 with CP, specially when you never worked with Siemens plc's. But of course more expensive...

 

[manmeetvirdi]

Hi there

You can use TP170B,Op170B(both mono)orMp370(coloured) with simens 315-2dp.
You can either connect them to MPI or Profibus port on CPU.You need not do anything in software for establishing conection between CPU and OP.Only thing is that you need to generate tags having the address used in plc software.
Its very easy.