Siemens Simatic RTU303xC Series Operating Instructions Manual page 23

In the Update mode, the RTU runs through the following steps:
● Read the inputs and, if enabled, the GPS position (RTU3031C) that were configured for
the current cycle.
● Processing of the program blocks
● Writing the outputs
● Saving the process data in the send buffer when telecontrol communication is enabled
● Saving the process data data on the SD card (with Logging activated)
After updating, the RTU returns to sleep mode, or changes to the communication mode if
this is configured. The update cycle and communication cycle can also run independently of
each other.
In addition to the configured update cycle, the RTU changes from the sleep mode to the
update mode when configurable events occur. The following events can be configured:
● Value change at the analog input "AI0"
● Edge change at a digital input
● Triggering of timers of program blocks, for example with a pulse generator or with the
on/off delay.
● Manual value change of a tag in WBM
Note that configured events lead to higher current consumption.
Communication mode
In the Communication mode, the RTU performs the following tasks:
● Activating the internal mobile wireless modem or the LAN interface and an external router
(via configurable control outputs of the RTU)
● Sending the data messages to the configured communications partner in the master
station
● Sending stored messages / data (SMS messages, e-mails, FTP file transfer, Syslog)
● Synchronization of the time of day if configured.
● Diagnostics
In addition to the tasks listed above, in the communication mode a connection can be
established to the WBM of the RTU by the telecontrol server or the configuration PC. This
makes diagnostics of the RTU and maintenance work possible.
The times of the changeover to the communication mode can be configured as a cycle and
on the occurrence of events. After transferring data, the RTU returns to the sleep mode. As
long as there is no update cycle running.
Connection establishment as a result of receiving a wake-up SMS message from the
telecontrol server or from a mobile phone can be configured. Remember that this increases
the current consumption of the RTU. For more detailed information, refer to the section
Wake-up call / wake-up SMS (Page 240).
Service mode
The service mode is enabled by briefly pressing the (< 1 s) of the "WKUP" button.
RTU303xC
Operating Instructions, 06/2019, C79000-G8976-C382-06
Application and functions
1.3 Modes and operating modes
23