Siemens Simatic S7 Series

Program instructions
7.2 Clock
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
167
7.2.2
Read and set real-time clock extended
LAD / FBD
STL
Description
TODRX T
The Read real-time clock extended instruction reads the current time, date, and
daylight saving configuration from the PLC and loads it in a 19-byte buffer begin-
ning at the address assigned by T.
TODWX T
The Set real-time clock instruction writes a new time, date, and daylight saving
configuration to the PLC using the 19-byte buffer data that is assigned by byte
address T.
Non-fatal errors with ENO = 0
SM bits affected
• 0006H Indirect address
• 0007H T data error
• 0091H Operand out of range
None
Input
Data type
Operand
T
BYTE
IB, QB, VB, MB, SMB, SB, LB, *VD, *LD, *AC
Note
READ_RTCX, SET_RTCX programming tips
Invalid dates are not accepted. If you enter February 30, for example, a time
-of-day non-
fatal
error will occur (0007H).
Do not use the READ_RTCX / SET_RTCX instructions in both the main program and in an
interrupt routine. A READ_RTCX / SET_RTCX instruct
ion in an interrupt routine cannot
execute, while another READ_RTCX / SET_RTCX instruction is executing. In this case,
system flag bit SM4.3 is set, indicating that two simultaneous accesses to the clock were
attempted resulting in a T data error (non
-fatal error 0007H).
The time
-of-
day clock in the CPU uses only the least significant two digits for the year, so for
the year 2000, the year is represented as 00. However, user programs that use the year's
value must take into account the two
-digit representation.
Leap year is correctly handled through year 2099.