48 Rockwell Automation Publication 440R-UM012E-EN-P - November 2018
Chapter 9 Example Operational Sequence Diagrams
3. You press the Start button and the motor begins to accelerate and the
proximity sensors generate pulses. At some point, the speed becomes
faster than the safely limited speed set by SW2 on the GLP safety relay,
but stays below the maximum safe speed. This speed is the normal
machine operating speed during production.
4. Later, you want to enter the cell. You press the Unlock Request button.
Upon release of the button:
• The signal at Y32 goes HI, which commands the PowerFlex 525
drive to go to its preconfigured safe slow speed.
• The 51/L61 indicator on the GLP safety relay starts blinking,
waiting for the speed to reduce below the safely limited speed.
5. The pulses from the proximity sensors reduce in frequency. When they
indicate that the speed is below the safely limited speed, the GLP safety
relay begins the Frequency Measurement Time to verify that the speed is
maintained below the SLS1 setting. The motor continues turning at the
safe speed.
6. At the end of the Frequency Measurement Time, the gate terminal 51
output turns ON to unlock the gate (the 51/L61 indicator turns OFF).
The motor continues turning at the safe speed. You enter the
manufacturing cell, perform the required production functions, and
then leave the cell.
7. You press and release the Reset and Lock Request. Upon release of the
button:
• The Lock signal (terminal 51) goes LO (the 51/L61 indicator turns
ON).
• The Gate Status signal (S12/S22) goes HI, which indicates that the
door is closed and locked.
• The Y32 signal then goes LO and the PowerFlex 525 drive ramps up
to normal production speeds.
8. During the normal production process, you press the Stop button. The
motor decelerates to a stop. When the speed drops below the maximum
safe slow speed, the GLP safety relay does not change the door status.
9. You press the Start button. The motor ramps up to production speed.
10. The motor exceeds the maximum speed set by SLS2 (a fault condition).
The GLP safety relay detects the speed by the proximity sensors and
immediately turns the X14/X24 outputs and L11 stops oscillating. The
EM outputs turn off and the PowerFlex 525 drive executes a coast-to-
stop. Terminal Y32 goes HI and the safety gate remains locked. The
PWR/Fault indicator is green with 4x flashing red to indicate overspeed.
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