Siemens S7-200 alike

Hello,

I have an aplication using a Siemens S7-200 PLC, with a very low end and easy logic. I would like to expand my application to multiple machines on which i basically just count +1 from sensors. Since S7-200 is not that cheap (for my purpose) im looking for an alternative on which i can apply the same logic as i have on existing S7-200 PLC.

All I require a mudbus connection and at least 6 digital IO for my sensors. No need for outputs or anything else. Can you help me pick a good alternative within resonable price range?

Thanks and best regards

I dont think you will find much cheaper then the 200 series... plus when you add the cost of reprogramming into new logic then another CPU would far surpass the cost of the 200

I have some 200's cheap and not so cheap, but the shipping would be expensive so it may be better to find a local seller

Hello

Perhaps Samba model from Unitronics is a cheaper alternative?
This is Plc and Hmi in one unit,had Some one board I/o and cost about 250 euro.
www.unitronics.com

Kind regards
Henny

Automation Direct Click. 69 USD.

Hi,

I hear that Fatek PLCs have alot of bang for the buck..

My 2 cents

Ahh, bad news for me... (not from you)

The modbus option was, well i hoped for, an upgrade. As i'm checking the software now, it seems the modbus connection was never coded till completion so i guess i'll have to stay with serial connection,

In that case...now i was using S7-200 with PPI/PC cable connected to RS232 on my server. As i heard, S7-200 is obsolete. What do you purpose i buy instead? i would need like 10 of sets like that. So if it exist a PLC with RS232 would be great. S7-1200, so i dont need a reprogram?

But then a new problem. Due the long range i will probably need a RS232 to ethernet adapter and a virtual ports on server (thats why i was hoping for modbus). I suppose that will do the trick, any suggestion on adapter?

Many thanks in advance

The only PLC that can use the program that you have is the S7 200, if you use any other model you will need to re make the program, even the S7 1200 uses different software

Yes the 200's are going away but it will be some time before they are gone

If you are thinking about a redo of your project (s) then yes the 1200 would be a great option and should be an easy write for your program if you only have 6 inputs and built in Ethernet ports and this would help with your 'long range'

This is the CPU (S7-1200) we use on our digital trainers http://support.automation.siemens.com/WW/view/en/61520895

Not sure of your cost over there but I think it would be a good option

Thank you all for your answers!

Of course im not finished with them yet
I can confirm, that my application only works with Serial RS232 communication. So atm with S7-200 through the cable convertor PPI - RS232. If i buy a S7-1200 i would like to avoid buying cables. Is that possible? Can you refer me to a correct modules that goes with that CPU. So i will only need one cable for programming CPUs and not for communication, as i will have 10 of S7-1200s.

I thought you said that you could use Ethernet? the S7-1200 is Ethernet not RS232, you can buy a module but that will be an added expense, if you can use Ethernet then you do not need any cables other then a Ethernet cable

ecvetek said:

Thank you all for your answers!

Of course im not finished with them yet
I can confirm, that my application only works with Serial RS232 communication. So atm with S7-200 through the cable convertor PPI - RS232. If i buy a S7-1200 i would like to avoid buying cables. Is that possible? Can you refer me to a correct modules that goes with that CPU. So i will only need one cable for programming CPUs and not for communication, as i will have 10 of S7-1200s.

Click to expand...

The 1200 does not support PPI.

The 1200 is programmed via ethernet, so you don't need to buy a special cable for that. It can also control Profinet devices over Ethernet. That would

You will need the communications card (goes on the left side) that supports RS232, if you want RS232. You also need to ensure that it supports whatever kind of RS232 protocol you need. It supports ASCII, which is the typical case, but many more exist.

If you are looking for Modbus RTU, you would need the RS485 module. If you want Modbus TCP, then you can use the built in Ethernet port. There are pre-made instructions included for both protocols, so it wouldn't be too hard to implement if you want to try that route.

geniusintraining said:

I thought you said that you could use Ethernet? the S7-1200 is Ethernet not RS232, you can buy a module but that will be an added expense, if you can use Ethernet then you do not need any cables other then a Ethernet cable

Click to expand...

Yes i did say that at first time, but then i figured out im limited to serial RS232. Now i have the idea to buy S7-1200 with RS232 modul and then a converter to ethernet with an option of setting up a virtual COM port at the end point on the server. Will that work? Because my software is only able to comunicate with RS232 COM ports. So i can not help myself with build in ethernet as i can not set a virtual COM port at the other end on the server. Keep in mind i would like to replace my S7-200 with PPI to RS232 communication.
Any more ideas?

Thanks and regards.

ecvetek said:

Any more ideas?

Click to expand...

Yes the 1200 has RS232 if you were to purchase the modules, but now you are looking to build a complete system... If you have a 200 then maybe just add a Ethernet card? I sell them http://www.plccable.com/siemens-6gk7243-1ex01-0xe0-s7-200-ethernet-6gk72431ex010xe0/ That maybe the cheapest option if you are using the 200 now, the 200 has a RS485 (PPI) port, you can add the Ethernet card?

If not then it maybe best if you told us the project details that you are working on and we may have better advice, not sure of the complete scope

geniusintraining said:

Yes the 1200 has RS232 if you were to purchase the modules, but now you are looking to build a complete system... If you have a 200 then maybe just add a Ethernet card? I sell them http://www.plccable.com/siemens-6gk7243-1ex01-0xe0-s7-200-ethernet-6gk72431ex010xe0/ That maybe the cheapest option if you are using the 200 now, the 200 has a RS485 (PPI) port, you can add the Ethernet card?

If not then it maybe best if you told us the project details that you are working on and we may have better advice, not sure of the complete scope

Click to expand...

I have a software, that is constantly connected to PLC and takes values form 6 digital inputs. On those inputs i have connected sensors which count pieces. And right now, i have a S7-200 with PPI to PC cable, connected directly to PC within 1meter range. The software is only able comunication with PLC thrugh COM port eg. RS232. No other option, i tested! And now i want 10 more sets like this, but i want to use only one computer for all of it. But the range from PC to PLC will be in that case, from 100meters on... And i can not have that much cable for RS232 communication. Thats why i wanted to do a RS232 with ethernet adapter, and on server (the main PC) a software that comes with adapter - virtual COM ports. In that case i will be able to communicate with PLCs even if they are actually connected on ethernet.

Back to idea, S7-1200 with RS232 plus ethernet adapter and a virtual COM port on PC? Even if i have S7-1200 only with ethernet connector, i will not be able to convert it to RS232 on server. RS232 industrial adapter will be 100€, for everything else i dont know the approx. prices...yet

The software is only able comunication with PLC thrugh COM port eg. RS232. No other option, i tested!

Click to expand...

What software ?
What communications driver is used ? (driver, not the protocol).

The idea of multiple Ethernet/serial adapters with virtual COM ports plus a PPI to serial adapter for each PLC sounds as a cludge. OK as a workaround for one or two legacy PLCs that one must support, but should be reconsidered for a new project with that many PLCs.

If the software is really the limiting factor here, you should try harder to get this changed or updated. It does not sound good that some software can only work with Modbus RTU. Nothing wrong about Modbus RTU, but it is not state-of-the-art and anything you create new today will probably have to last many years.

How about changing the PC software? I think you will have the same issues with the 1200 or 200, if you change your data software then you can just install the 1200 (with ethernet port) and they all can connect to the PC via Ethernet

What is the software you have collecting the data and what is it doing with it?

This is the 1200 that I use with my digital trainers and they are priced good for what you get 6ES7212-1BE31-0XB0 http://support.automation.siemens.com/WW/view/en/61520895 I use 1214c with my analog models but I think its a overkill for this