Siemens SIMATIC NET PROFIBUS - Manual (Page 24)

PROFIBUS NETWORKS
1-14
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
1.2.6 Transmission Technique for Wireless Infrared Technology
The wireless PROFIBUS network uses infrared light for signal transmission. The
only transmission medium is a free line-of-sight connection between two nodes.
The maximum distance covered is approximately 15 m. Wireless networks are
implemented using infrared link modules (ILM). The nodes to be networked are
attached to the electrical port of the ILM.
Advantages:
S
High mobility of attached plant components (for example trolleys)
S Coupling and decoupling from the fixed network with no wear and tear (for
example substitute for a slip ring)
S
Coupling without cable installation (temporary setup, inaccessible areas)
S
Not protocol dependent
S
Electrical isolation between nodes and hardwired network
Restrictions
S Transmission rate <= 1.5 Mbps
S
Free line-of-sight path required between nodes
S
Maximum distance covered <= 15 m
S Only for single master networks
Characteristics of the Wireless Infrared Transmission Technique
The wireless infrared transmission technique has the following characteristics:
Network topology: Point-to-point
Point-to-multipoint
Medium: Free space with line-of-sight path
Maximum link length: 15 m
Transmission rate ILM: 9.6 Kbps, 19.2 Kbps, 45.45 Kbps, 93.75 Kbps, 187.5 Kbps,
500 Kbps, 1.5 Mbps
Number of nodes: Maximum 127 per network