Siemens SIMATIC NET PROFIBUS manual Topologies of Wireless Networks, Maximum Length of a Link

Topologies of SIMATIC NET PROFIBUS Networks

2.3Topologies of Wireless Networks

Infrared Link Module (ILM)

In SIMATIC NET, wireless PROFIBUS networks are implemented with the “Infrared Link Module (ILM)”.

Figure 2-8 PROFIBUS ILM

Maximum Length of a Link

Regardless of the transmission rate, the maximum length of a link is 15 m. The infrared light used for data transmission is radiated at an angle of +/- 10o around the mid axis. This means that at a distance of 11 m, an ILM illuminates a circular area with a diameter of 4 m. The communication partner must be within this illuminated area. There must be an uninterrupted line-of-sight path between both ILMs. The ILMs are suitable for transmission rates of 9.6 Kbps to 1.5 Mbps.

Point-to-Point Link

To implement a point-to-point link, two ILMs are positioned opposite each other so that each is located within the infrared light cone of the other. The maximum distance between two modules is 15 m.

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	6GK1970-5CA20-0AA1 Release 2 05/2000