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communication between plc and microcontroller
Created by: studentumair at: 6/1/2010 3:29 AM (3 Replies)
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| 6/1/2010 2:41 PM | |
Joined: 12/9/2009 Last visit: 4/18/2024 Posts: 156 Rating:
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Hello, Which CPU do you use in SIMATIC S7-300? Do you use any communication modules in your S7-300 station? Which communication protocol do you use for data transmission? Under the following link you can find an overview about the communication protocols which are supported by the S7-300/400 CPUs and communication moduls: http://support.automation.siemens.com/WW/view/en/24352751 Here you can find the technical data of the S7-300 CPUs: http://support.automation.siemens.com/WW/view/en/12996906 Best regards Little Holmes |
| 6/1/2010 5:53 PM | |
Joined: 9/27/2006 Last visit: 12/5/2024 Posts: 12300 Rating:
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Hello umair; Have a look at the following link: http://modbus.control.com/thread/1026226844 First, this is the Modbus community website, so you can find details on the Modbus protocol and its implementation on the site. seconfd, the thread mentions someone developping Modbus protocol on a PICs microcontroller. maybe he could help you out. One you have the microcontroller setup as a Modbus slave, all (!) you have to do is procure a CP 341, the Modbus master driver and a lot of patience... Hope this helps, Daniel Chartier |
| 6/2/2010 8:31 AM | |
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Posts: 45 Rating:
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Hello, Much depends on wether you are able to purchase additional S7 hardware modules for communication. Firstly, you must choose the physical media for your communications. Shold it be RS232, RS485, current loop (TTY), Modbus or something more exclusive? Serial communications with S7 in a common approach will require one of following modules (depends on physics chosen):
Naturally, you have to pay average 300 to 800 euro for one of that communication modules. Notion of RS485/RS232 does not allow you to use it in PLC without communication modules described above (I mean in a decent transfer speed). However, if you are not enforced to use them and want to save your money, there are several ways to implement the communication without any CP at all. At that point much will depend on your fantasy For a duplex communications I would recommend to implement something like SPI. Such an interface is less vulnerable on transfer speed deviation and is more robust in a PLC implementation. I have long before implemented a one-way communication with S7-CPU and microcontroller using no more than two wires, both supply 24V and data. Please understand me right, I dont incline anybody to use hand-made communications. Naturally, using standard S7 CP modules is the most stable solution, but not the cheapest. Just deside for your own... Hope this will help, Sergey Shapovalov |
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