Hardware Interrupt Evaluation - Siemens SIMATIC CM35 Manual

Timer Operating Mode
7.5

Hardware Interrupt Evaluation

7-12
When in timer mode, the CM35 can trigger a hardware interrupt for the
following events.
- - Timer expired
- - Timer failure
The user must wire digital outputs 1 to 8 with digital inputs 1 to 8 (see chap.
7.1) so that the switching status of the output can be monitored with the re-
lated input. If the output setpoint state differs from the input actual state, the
following occurs based on the parameterization.
No interrupt triggered
S
Group interrupt triggered ! Failure of a timer
S
Selective interrupt triggered ! Timer failure
S
The CPU must have a hardware interrupt OB (OB 40) for the interrupt evalu-
ation.
The start information of OB 40 contains the following.
- - Variable OB40_MDL_ADDR contains the base address of the module
which triggered the interrupt.
- - Variable OB40_POINT_ADDR contains information on the event
which triggered the interrupt.
Variable OB40_POINT_ADDR consists of four bytes. The hardware interrupt
information of the CM35 in timer mode is stored in local byte 10 (timer fail-
ure) and local byte 11 (timer expired) of OB 40.
By evaluating local bytes 10 and 11, you can tell which timer triggered an
interrupt. Remember that more than one bit can be set.
Note
When a failure occurs on one of the timers (e.g., wire break), this is reported
once for the applicable channel with a hardware interrupt.
The reaction to the hardware interrupt (e.g., the malfunctioning timer chan-
nel is no longer addressed by the user program) is specified by the user pro-
gram (OB 40 call). All other timer channels remain functional.
After the malfunction is corrected (e.g., wire break fixed), a STOP/RUN
transition of the CPU must be executed. Another method is to call SFC 57
²PARM_MOD.² If error correction was successful, the malfunction is no
longer reported after a STOP/RUN transition or an SFC 57 call. If the mal-
function is still present, another hardware interrupt is triggered.
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618