Sto Diagnostics; Figure 2-43: Sto Timing - Aerotech XR3 Hardware Manual

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XR3 Hardware Manual

2.11.4. STO Diagnostics

Activation of STO means removing power from the XR3's STO inputs. This is typically done by pressing the
emergency stop switch. The XR3 initiates a diagnostic check every time the STO is activated after the
Diagnostic Test Delay Time has elapsed. The diagnostic check verifies that each channel has entered the
safe state. The XR3 is held in the safe state if it determines that one of the channels has not properly entered
the safe state. An open circuit or short to 24 V in either STO channel will result in this condition (refer to
Section
2.11.3.). The Status Utility screen can be used to verify the levels of the STO input signals while
trouble shooting.
In order to meet the listed SIL level, the STO circuit must be activated (power removed from both inputs)
according to the interval specified in
Table 2-52:
STO Timing
Time
Description
T1
STO Delay Time (STO input active to motor power off)
STO deactivated to motor power on (the software is typically con-
T2
figured so that the motor does not automatically re-energize).
T3
Diagnostic Test Delay Time
The software is typically configured to execute a controlled stop when the STO state is first detected. If
power is reapplied to the STO inputs before the STO Delay Time, an STO hardware shutdown will not occur
but a software stop may, depending on the width of the STO pulse. The controller will ignore STO active
pulses shorter in length than the STOPulseFilter parameter setting.
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Chapter 2: Installation and Configuration
Table
2-49.
Figure 2-43:
STO Timing
Value
450-550 msec
< 1 msec
550-610 msec
79

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