Ethernet and H1-Bus?

H1 is ethernet with an additional application layer called TF (Technical Functions). This allows equipment to talk to each other more efficiently thus improving performance. I believe that the association layer is layer 7 in the ethernet spec. Hope this helps.

Georg Hellack GHF automation GmbH


H1 was the former name given by SIEMENS to their Ethernet based PLC communication. It is now called 'Industrial Ethernet'. The name 'H1' relates to the physical (ethernet) as well as the protocol layer. There are two flavors, one for low-level access with some protocol on OSI transport layer (COTP TP4). The protocol is decribed in the manuals for the S5 comm. processor board and is often called 'H1 protocol'. Then there is a more sophisticated protocol TF, which handles typified data. The philosophy is very similar to MAP/MMS. There is also now a TCP/IP-based version, which uses RFC1006.

Best regards,

Georg Hellack
GHF automation GmbH

Ralph Mackiewicz

This is H1:

Layer 7 Application: TF (Technical Functions)
Layer 6,5: Null
Layer 4, Transport: Class 4 ISO/OSI Transport
Layer 3, Network: CLNP without ES-IS (static routing only)
Layer 2, Data Link: IEEE 802.2 LLC and IEEE 802.3 MAC
Layer 1: Physical: Industrially hardened 10Base5 (options now available).

This is Ethernet:

Layer 2: IEEE 802.3 MAC
Layer 1: 10Base2, 10Base5, 10/100BaseT, 10BaseF, etc. etc.


Ralph Mackiewicz