Siemens SCALANCE XF200 - Special Features of IRT and PRO Variants

Functions
SCALANCE X-200
12 Operating Instructions, 03/2015, C79000-G8976-C284-06
Special features of the X-200IRT IE switches
The IRT variants were designed specifically for setting up Industrial Ethernet networks with
isochronous/clock synchronous real-time communication. In addition to the properties named
above, the IRT switches also provide the following functions:
● IRT communication based on the combination of the switching methods cut through and
store and forward.
● Fast media redundancy thanks to an integrated redundancy manager for Fast Ethernet.
● Standby redundancy
Special features of the PRO variants
The devices with the "PRO" supplement are designed with degree of protection IP65/IP67
for use outside a cabinet.
Frame delay times
The number of IE Switches X-200 connected in a line influences the frame delay.
Note
Frame delay time with X-200 without IRT
When a frame passes through X
-200 IE switches, it is delayed by the Store&Forward
fun
ction of the X-200 IE switches.
•
With a 64 byte frame length by approx. 10 microseconds (at 100 Mbps).
•
With a 1500 byte frame length by approx. 130 microseconds (at 100 Mbps).
This means that the more IE
Switch X-200 devices the frame passes through, the longer the
frame delay.
Note
Frame delay time with X-200 with IRT
The more X
-200IRT IE switches a frame runs through, the higher the frame delay. By using
the "cut through" switching mechanism, the X
-200IRT IE switches are ideal to meet the real-
time requirements of PROFINET.
Cut through is, however, not possible:
•
Between a port set to 10 Mbps and a port set to 100 Mbps.
•
When two packets are to be sent at the same time on one port.
In this case, an X-200 IE switch changes to Store&Forward and the delay increases.