Siemens SIRIUS 3RW5 - Bus connection cable and bus connector

Description
3.4 Connection monitoring
SIRIUS 3RW5 Modbus communication module
Equipment Manual, 03/2020, A5E43676481002A/RS-AC/003
27
3.4 Connection monitoring
Connection monitoring function - "TCP keep-alive monitoring"
To avoid blocking the communication connection permanently if the communication partner
fails, Modbus TCP provides the "TCP keep-alive monitoring" function for monitoring the
connection.
The following parameters can be permanently set for this purpose:
● Keep-alive time: 300 s
● Keep-alive maximum attempts: 1
● Keep-alive interval: 75 s
If no TCP data transmission is detected within 375 seconds, the "TCP keep-alive monitoring"
function signals connection broken and ends the communication connection automatically.
On a broken connection, the 3RW5 soft starter responds in accordance with the behavior
described in chapter Operation on failure of the bus connection to the controller (Page 88)
(Parameter "Response to CPU/Master Stop").
Connection monitoring function - Access monitoring of the control source
An independent connection monitoring function monitors access by the authorized
Modbus TCP client or the Modbus RTU master within the access monitoring time. In the
case of Modbus TCP, only the Modbus TCP client, which is the first to set up a
communication connection to the server, is authorized for this access.
An access (write or read) of the Modbus TCP client to the server or of the Modbus RTU
master to the slave (e.g. process image outputs (PIQ), parameters) must be repeated
regularly. If the write or read process is not repeated for the duration of the access
monitoring time, the 3RW5 soft starter interprets this condition as a broken connection to the
Modbus TCP client or Modbus RTU master. The 3RW5 soft starter responds in accordance
with the behavior described in chapter Operation on failure of the bus connection to the
controller (Page 88) (Parameter "Response to CPU/Master Stop").
Note
3RW5 Modbus TCP communication module with a firmware version lower than V1.1
With a 3RW5
Modbus TCP communication module with a firmware version lower than V1.1,
a write access by the Modbus
TCP client to the server must be repeated regularly. O
nly read
access
throughout the access monitoring time prevents a broken connection with the
Modbus
TCP client.
You will find the setting options for the "access monitoring time" in chapter
Access monitoring time (Page 87). The factory setting is 5 seconds.