Safe Direction (Sdi) - Siemens Simatic ET 200SP Equipment Manual

4.9.3

Safe Direction (SDI)

Safe direction (SDI) monitoring
SDI monitoring is initiated whenever the "Enable Safe Direction" bit is set in the control
interface and subsequently processed by the F-TM Count module. SDI monitoring terminates
whenever the "Enable Safe Direction" bit is reset in the process output image and
subsequently processed by the module.
Each time safe direction monitoring is initiated, the current position and the specified safe
direction are stored. The "Safe Direction Event" bit is set whenever a movement is detected in
the unsafe direction and exceeds the configured "Monitoring tolerance". The "Monitoring
tolerance" is measured from the farthest position achieved in the safe direction. As
movement progresses in the safe direction, the tolerance of movement in the unsafe
direction shall be measured from this farthest position.
Monitoring tolerance is configured in counts. The safe direction is specified in the process
output image.
Once set, the "Safe Direction Event" bit remains set and counting continues after the event is
triggered. The "Safe Direction Event" remains set until the "Reset Safe Direction" bit is set to 1,
until a power cycle, or until a new parameterization is loaded.
Configuring a value of 0 for the monitoring tolerance results in the "Safe Direction Event"
being set immediately after the first pulse in the unsafe direction.
Safe direction monitoring continues when counting is suspended and SDI monitoring
is enabled.
Since there is no active counting operation when counting is suspended, this safety function
becomes ineffective. This can result in unexpected machine or process operation, which can
cause death, severe personal injury, and/or property damage.
You must ensure steps outlined in safety standards applicable to your system are followed
before the event bit is reset.
ET 200SP F-TM Count 1x1Vpp sin/cos HF (6ES7136-6CB00-0CA0)
Equipment Manual, V1.0, 01/2021, A5E47073911-AA
WARNING
Parameters/address space
4.9 Safety functions
57