WAGO-I/O-SYSTEM 758
Appendix
59
758-915
Bluetooth
®
ETHERNET Gateway
Manual
Version 1.1.0, applicable from FW/HW Version 01/01
8.2
Time Response
Optimal time response is achieved when a WEG is operated together with another
WEG. Radio transmission then requires about 7 ms. The reply time for double
transmission, such as for a ping, is about 14 ms.
On account of the limited bandwidth of the transmission path, a delay of around 8
ms must exist between transmissions of ETHERNET data packets. You must
therefore set the cycle time appropriately for the bus master for transmission of
cyclic fieldbus data.
8.2.1
Time response example: PROFINET
Recommendations for using a WEG-WEG bridge for transmitting data for a
PROFINET network are given below.
In the event that outside data, such as from the IP protocol family, is present in
addition to the PROFINET network data, PROFINET optimization should be
activated, to ensure that the PROFINET data is handled with a higher priority.
Failure to activate this option can result in the outside data occupying
transmission bandwidth, making it unavailable for transmission of the PROFINET
data.
The following minimum cycle times shall not be violated if the master is operated
at one end of the wireless link and the smaller network with the slave nodes at the
other end:
Table 30: Cycle Times between Master and Smaller Network Consisting of Slave Nodes
Number of slave nodes
Minimum cycle time [ms]
1
≥ 10
2
≥ 20
3
≥ 30
4
≥ 40
The data given in the table is based on typical applications, which tolerate
sporadic packet loss or delays and which only signal an error after one or two
repeated packet loss, for example.
When protocol or application data that must be in real-time is transported via the
cyclic bus, the mandatory timeout must be at least four times the current cycle
time, plus the one-way transfer time. Normally, a value less than that indicated in
the table below should not be selected:
