Siemens PLC User Manual

PLC to PLC Communications

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Agenda

-PUT/GET S7 Communications

-Modbus/TCP

-Open User communications

-I-Device

-OPC UA

-Flexible F-Link

-Libraries

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PUT/GET

Advantages

•Single sided – only needs to be programed in one PLC

•Works in all Simatic PLC’s

•Independent of the communication media

•Can be used on all S7 data areas

•Wizard is available for setup in TIA

Disadvantages

•No security

•Blocked by default on the S7-1200 and S7-1500

•Data blocks have to be unoptimised

•Only small amounts of data can be transferred <160bytes

•No acknowledgement of transfer this needs to be

engineered if needed

• Always takes a connection resource

https://support.industry.siemens.com/cs/au/en/view/82212115

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Modbus/TCP

Advantages

• Cross vendor communication

• Built in diagnostic

• Routable over Ethernet

• Optimized Data blocks are supported

• Defined communications timeout

Disadvantages

• No security or encryption

• No setup wizard

• Server/Client blocks must be programmed

Great for communication to 3rd party devices but can be used for PLC to PLC communications

https://support.industry.siemens.com/cs/au/en/view/102020340

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Open User Communications

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TCP, ISO on TCP or UDP

	TCP	ISO on TCP	UDP
Speed	Rapid	Rapid	Very Rapid
Quantity	Medium to Large	Medium to Large	Small to Medium
	S7-1500: 64kB	Same as TCP	S7-1500: 2kB
	S7-1200: 8kB		Others: 1472B
	S7-300/400: 32kB
Connection	Connection	Connection	Connectionless
	orientated	orientated
Acknowledgment	Acknowledgment of	Acknowledgment of	Only Acknowledges
	sending and receiving	sending and	sending and not
	of data	receiving of data	that it was received
Systems	Siemens and 3rd	Siemens	Siemens and 3rd
	Party		Party

https://support.industry.siemens.com/cs/au/en/view/26171811

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