Siemens SINUMERIK 840D sl Function Manual page 512

Data descriptions
9.7 System variable
Difference between $VA_IS and $AA_IM
Both variable $VA_IS and variable $AA_IM can be used to read actual values.
Table 9-5
Variable
$VA_IS
$AA_IM
Reference: /PGA/, Programming Manual Job Planning
System variables $A_XFAULTSI and $VA_XFAULTSI
For crosswise data comparison errors between the NCK and SINAMICS S120, the response
depends on the actual operating state:
● SBH, SG, SE, SN or n<n
causes a transition from Stop F to Stop B - which in turn initiates the fastest possible braking
of the axis. A STOP A is then initiated and the pulse enable is cancelled.
● SBH, SG and n<n
active: In this case, a STOP F due to a crosswise data comparison error does not result in
any further action - only Alarm 27001 or 2710x is output that provides information.
Processing then continues.
This chain of responses is not altered to ensure the appropriate level of safety for personnel.
To allow responses to a crosswise data comparison error, system variable $A_XFAULTSI is
used to display that a crosswise data comparison error has occurred on a particular SI axis.
Retraction can then be initiated as a response to this system variable.
Further, an axis-specific system variable $VA_XFAULTSI[<axis name>] has been introduced
so that, if necessary, axis-specific responses can be applied.
The system variables are updated independent of whether SI monitoring functions are active
or inactive.
$A_XFAULTSI
Information about STOP F for a safety axis:
Bit 0 = 1:
Bit 1 = 1:
$VA_XFAULTSI[X] (X = axis identifier)
512
Difference between $VA_IS and $AA_IM
Meaning
Reading the actual value used by SI
For the actual value, instead of $AA_IM, variable $VA_IM should be used
synchronization active: A crosswise data comparison error
x
synchronization inactive and SE/SN not used or Stop C/D/E already
x
In a crosswise data comparison between NCK and drive of any particular safety
axis, an actual value error was detected.
In the crosswise data comparison between NCK and drive of any axis, an error
was detected and the delay time until Stop B is initiated
($MA_SAFE_STOP_SWITCH_TIME_F) for this axis is either running or has al‐
ready expired.
Note: The bit is only set if a delay not equal to 0 is configured.
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated