Time Of Day Interrupts; Set_Tintl (Set Time Of Day Interrupt) - Siemens S7-1200 System Manual

Table 8- 94
RET_VAL (W#16#....)
0000
8090
80B2
8.4.3

Time of day interrupts

If an attacker can access your networks through Network Time Protocol (NTP)
synchronization, the attacker can possibly take limited control of your process by shifting
the CPU system time.
The NTP client feature of the S7-1200 CPU is disabled by default, and, when enabled, only
allows configured IP addresses to act as an NTP server. The CPU disables this feature by
default, and you must configure this feature to allow remotely-controlled CPU system time
corrections.
The S7-1200 CPU supports "time of day" interrupts and clock instructions that depend upon
accurate CPU system time. If you configure NTP and accept time synchronization from a
server, you must ensure that the server is a trusted source. Failure to do so can cause a
security breach that allows an unknown user to take limited control of your process by
shifting the CPU system time.
For security information and recommendations, please see our "Operational Guidelines for
Industrial Security"
security/Documents/operational_guidelines_industrial_security_en.pdf) on the Siemens
Service and Support site.
8.4.3.1

SET_TINTL (Set time of day interrupt)

Table 8- 95 SET_TINTL (Set date and time of day interrupt with DTL data type)
LAD / FBD
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
RET_VAL parameter
WARNING
(http://www.industry.siemens.com/topics/global/en/industrial-
SCL
ret_val := SET_TINTL(
OB_NR:=_int_in_,
SDT:=_dtl_in_,
LOCAL:=_bool_in_
PERIOD:=_word_in_
ACTIVATE:=_bool_in_);
Description
No error
OB does not exist or is of wrong type.
OB has no attached event.
Description
Set a date and time of day interrupt. The
program interrupt OB can be set for one
execution, or for recurring execution with
an assigned time period.
Extended instructions
8.4 Interrupts
337