How many method of PLC 2 PLC communication in siemens
In Siemens PLCs, there are multiple methods for PLC-to-PLC communication, depending on the PLC models, network protocols, and project requirements. Here are the most commonly used methods:
1. Industrial Ethernet (TCP/IP & PROFINET)
a) GET/PUT (S7 Communication)
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Used for simple data exchange between two PLCs.
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Requires one PLC to have GET/PUT enabled in CPU settings.
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Pros: Easy to implement, no additional hardware needed.
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Cons: Unidirectional (one PLC must request data from the other).
b) S7 Communication (S7-300, S7-400, S7-1200, S7-1500)
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Uses the S7 Protocol (ISO on TCP or PROFINET) for bidirectional communication.
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Requires "BSEND/BRECV" instructions (S7-300/400) or "TCON/TSEND/TRCV" (S7-1200/1500).
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Pros: Reliable and supports acknowledgment.
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Cons: More complex to set up compared to GET/PUT.
c) OPC UA Communication
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Uses the OPC UA Server/Client architecture.
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Requires an OPC UA-enabled PLC (like S7-1500) or an OPC UA Server (PC-based or external device).
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Pros: Secure and standardized for industrial IoT (IIoT).
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Cons: Requires additional licensing or configuration.
2. Fieldbus Protocols
a) PROFINET (Preferred for S7-1200/S7-1500)
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High-speed, Ethernet-based fieldbus for real-time data exchange.
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Uses Shared Device, I-Device, or RT/IRT communication.
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Pros: Fast, deterministic, and supports real-time communication.
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Cons: Requires a PROFINET controller/device configuration.
b) PROFIBUS DP (Preferred for S7-300/S7-400)
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Serial fieldbus for PLC-to-PLC communication.
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Uses DP Master/Slave configuration.
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Pros: Long-distance communication, robust.
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Cons: Slower than PROFINET, requires special hardware (DP modules).
c) MODBUS (RTU/TCP)
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Used for communication with non-Siemens devices and other PLCs.
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Modbus RTU: Uses RS485 (serial communication).
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Modbus TCP: Uses Ethernet (TCP/IP).
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Pros: Simple and widely used.
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Cons: No built-in diagnostics, slower than PROFINET.
3. Wireless & IoT Communication
a) MQTT (Message Queue Telemetry Transport)
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Used for IIoT and cloud-based applications.
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Requires an MQTT broker (on a PC or cloud).
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Pros: Lightweight, ideal for remote monitoring.
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Cons: Not suitable for real-time control.
b) 4G/5G Communication (With RTUs or Edge Devices)
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Uses cellular networks for remote PLC communication.
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Pros: Long-distance, cloud integration.
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Cons: Requires a SIM card and data plan.
4. Direct Hardware Communication
a) Shared Memory (Global Data Communication - GD)
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Available in S7-300/400.
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Uses Global Data (GD) to exchange small amounts of data without additional programming.
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Pros: Simple and fast.
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Cons: Limited data size.
b) IO-Link Communication
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Uses IO-Link Masters and Devices for sensor/actuator integration.
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Pros: Simple plug-and-play setup.
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Cons: Low-speed communication.
Comparison Table
| Communication Type | Speed | Complexity | PLC Compatibility |
|---|---|---|---|
| GET/PUT (S7 Comm.) | Medium | Easy | S7-300, S7-400, S7-1200, S7-1500 |
| S7 Communication (TSEND/TRCV, BSEND/BRECV) | High | Medium | S7-300, S7-400, S7-1200, S7-1500 |
| OPC UA | Medium | High | S7-1500 (OPC UA enabled) |
| PROFINET | Very High | High | S7-1200, S7-1500 |
| PROFIBUS | High | Medium | S7-300, S7-400 |
| MODBUS (RTU/TCP) | Medium | Easy | All PLCs (with Modbus support) |
| MQTT (IoT) | Low | Medium | S7-1200, S7-1500 (with MQTT support) |
| Global Data (GD Communication) | High | Easy | S7-300, S7-400 |
Which Method is Best for You?
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If you need fast communication → PROFINET or S7 Communication (TSEND/TRCV).
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If you want simple data exchange → GET/PUT.
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If you are connecting non-Siemens devices → Modbus RTU/TCP.
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If you need secure, cloud-based communication → MQTT or OPC UA.