Siemens SCALANCE XR-300M Compact Operating Instructions page 63

Mean time between failure (MTBF)
The values in the following table apply to the basic device without media modules.
Device version (power supply)
2 x 24 V DC
1 x 100 to 240 V AC
These values apply at 40 °C.
1)
In the calculation of the MTBF of a modular switch, the standard parts count applies; in other
words, the reciprocals of all component failure rates are added.
The reciprocal of this total id the MTBF of the entire assembly.
Full wire speed switching
At 100 Mbps
148810
84459
45290
23496
11973
9615
8127
Note
The following applies to IE Switches X-300:
The number of IE Switches X-300 connected in a line influences the frame delay time. When
a frame passes through the switch, this is delayed by the Store&Forward function of the
IE Switch X-300 by the following values:
● at 64 bytes frame length: Delay of approx. 10 microseconds (at 100 Mbps)
● at 1500 bytes frame length: Delay of approx. 130 microseconds
(at 100 Mbps)
This means, the more IE Switches X-300 a frame runs through, the higher the frame delay.
PRP compatibility
Device variant
XR324-12M
XR324-12M TS
* Information about the firmware version (V) as of which PRP is supported.
SCALANCE XR-300M
Compact Operating Instructions, 11/2019, A5E02661171-15
Number of frames per second
At 1000 Mbps
1488095
844595
452899
234962
119732
96154
81274
MTBF
1)
> 26 years
> 22 years
At a frame length of
64 bytes
128 bytes
256 bytes
512 bytes
1024 bytes
1280 bytes
1518 bytes
As of version *
V3.7.0
V3.7.2
Technical specifications
7.5 Other properties
63