1. Introduction to PROFINET and PROFIBUS
- PROFINET and PROFIBUS are two fieldbuses launched by the PNO organization, first implemented by Siemens.
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The two are not comparable; PROFINET is based on industrial Ethernet, while PROFIBUS is based on RS485 serial bus.
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Due to the different media, the protocols of the two are completely different and have no relation.
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Both have excellent real-time performance, attributed to their streamlined stack structure.
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Any development based on standard Ethernet can be directly applied to PROFINET networks.
2. Performance Comparison of PROFINET and PROFIBUS
1. Transmission Bandwidth
PROFIBUS: The maximum data transmission bandwidth is 12Mbps.
PROFINET: The data transmission bandwidth is 100Mbps.
2. Transmission Mode
PROFIBUS: The data transmission mode is half-duplex.
PROFINET: The data transmission mode is full-duplex.3. Consistent Data
PROFIBUS: The maximum consistent data is 32 bytes.
PROFINET: The maximum consistent data is 254 bytes.
4. User Data
PROFIBUS: The maximum user data is 244 bytes.
PROFINET: The maximum user data is 1400 bytes.
5. Transmission Distance
PROFIBUS: The maximum bus length at 12Mbps is 100m.
PROFINET: The bus length between devices is 100m.
6. Configuration and Diagnostics
PROFIBUS: Configuration and diagnostics require a dedicated interface template, such as CP5512.
PROFINET: Can use standard Ethernet network cards.
7. PG Access
PROFIBUS: If one PG accesses, it may cause communication issues.
PROFINET RT: One PG access may cause minimal response. For standard PROFINET access, it will not cause any issues.
8. Network Diagnostics
PROFIBUS: Requires special tools for network diagnostics.
PROFINET: Can use IT-related tools.
9. Master Station
PROFIBUS:
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Generally, there is only one master station on the bus. A multi-master system can lead to excessive DP cycle times.
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One interface can only act as a master or slave.
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The network location of devices cannot be determined.
PROFINET:
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All data types can be used in parallel.
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Any number of controllers can operate on the network.
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Multiple controllers do not affect IO response time.
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One interface can act as both a controller and an IO device.
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The network location of devices can be determined through topology information.
11. Terminal Resistance
PROFIBUS: The main source of faults on the bus comes from mismatched terminal resistances or poor grounding.
PROFINET: Does not require terminal resistances.
12. Communication Medium
PROFIBUS: Uses copper and fiber optics as communication media.
PROFINET: In addition to copper and fiber optics, wireless (WLAN) can also be used.
3. Message Comparison
4. Example of Bus Cycle Time
Extended Knowledge: PLC-Recorder can communicate with PLC based on PROFINET for data collection.