SMGM SYSTEM
68
8.4
Structure of the SMGM system - recommendation
8.4.1
Basics
TIPS AND RECOMMENDATIONS!
Recommendation: Structure of the SMGM system - specifications
The following recommendations for structuring the SMGM system apply for use with
PROFINET.
The consideration of the maximum number of participants/switch levels depends on
the number of connected PROFINET participants on the mobile SMGM module.
In the recommendation below, the connection of one PROFINET participant per mobile
SMGM-DI is assumed.
For the Ethernet switches, the data (Telegram throughput time = Delay) of the Siemens
SCALANCE X-200 without IRT is taken as the basis.
Since the SMGM system comprises stationary and mobile modules, it is to be considered as a dynamic net-
work. If a mobile module (SMGM-DI) changes the segment, it is assigned to a new, stationary module (SMGM-
SI). Due to this constant switching of the mobile modules, each piece of information that is vehicle-linked has
to run through another network. That causes delays in the transfer of the information. These delays relate to
the time that a switch requires to save and transfer the packets of a “new” device (segment change) (Store-
and-Forward method). To minimize the operational disturbances caused by the delays (the sum of each indi-
vidual delay) in the data transmission from the system supplied by the SMGM, the following recommendation
is made for structuring the SMGM network:
*STP protocols: Spanning-tree protocols
TIPS AND RECOMMENDATIONS!
Recommendation: Structure of the SMGM system
Determine the switch levels (max. 7) each time from the view of the SMGM modules.
When selecting the PLC, please make sure it is capable of processing the arising data
traffic.
Consideration
Specification
Topology
No ring topology
Cable lengths
max. 80m per LAN cable (green connection lines)
Switch levels
max. 7 (SMGM module = Switch)
PROFINET participant
Displayed system with one PROFINET participant per SMGM-DI
System controller - SMGM-SC
(red circle)
Recommendation to ensure a smooth functioning.
It must be ensured that the SMGM-SC can be reached at the top Ether-
net/PLC level. To guarantee smooth communications between the PLC
and the SMGM-SC, a maximum of one switch should be placed between
the PLC and the SMGM-SC.
Cable routes
In the cable routes between the SMGMs no other modules, devices, in-
verters, etc. are permitted to be used.
Network
The network should be used exclusively for the SMGM system.
Protocols
STP protocols* in the SMGM network must not be used / are not per-
mitted.
