Chapter
8
Studio 5000 Example Logix Code
GuardLink Commands
This chapter shows sample code for GuardLink commands.
Lock and Unlock
Figure 49 shows sample code to lock and unlock guard locking switches. Rung 9
uses an HMI input to unlock all switches in the GuardLink circuit. First, we move a zero into the LockCmd to clear out any previous lock commands. Then, we move a -1 into the UnlockCmd. The -1 is converted to a 1 for each tap.
Rung 10 uses an HMI input to lock all switches in the GuardLink circuit. First, we move a zero into the UnlockCmd to clear out any previous unlock commands.
Then, we move a -1 into the LockCmd. The -1 is converted to a 1 for each tap.
Rungs 11 and 12 provide an example of unlocking and locking a specific switch.
In this case, we move a 4, which is the third tap, instead of a -1.
Figure 49 - Unlock and Lock Commands
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Chapter 8 Studio 5000 Example Logix Code
Lock and Unlock a Nonlocking Device
When an unlock command is sent to a tap connected to a non-locking device
(like an E-stop), the GuardLink safety signal turns OFF. When a lock command is sent to a tap connected to a non-locking device, the tap turns ON. The following events occur when an unlock command is issued to an individual tap that is not connected to a locking switch.
Figure 50 , an unlock command is sent to tap 4 on Relay 1, GuardLink1. Tap 4 is
an E-stop.
Figure 50 - Unlock Tap 4
1.
The GuardLink safety signal turns OFF.
• The Link indicator on all taps changes to solid red.
• The Device indicator on all taps changes to blinking green. Tap 4 blinks green because the E-stop has not been pressed.
• The DG IN1 indicator changes to solid red.
• The DG output turns OFF.
2.
The following occurs in the Studio 5000 AOP:
• The GuardLink1.DeviceTrip.4 bit remains HI because the E-stop is not pressed.
• The GuardLink1.Trip bit remains LO, because no devices are tripped.
• The Relay1_GSR_DG.PtS12 is LO, because the GuardLink Safety signal is OFF.
• The Relay1_GSR_DG.SafetyInput01 is LO.
The unlock command for tap 4 must be cleared (set to 0), and a lock command must be sent to tap 4 to restore the GuardLink safety signal (
Figure 51 ).
Figure 51 - Lock Tap 4
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Studio 5000 Example Logix Code Chapter 8
Fault Reset Command to All GuardLink Taps
The fault reset command is used to power cycle a tap. In GuardLink 1.0, the DG relay does not know if a device connected to a tap is in a faulted state; the DG relay only knows that the tap is OFF. If the tap remains OFF, this state can indicate a device fault. A fault reset command can be sent to the tap to power cycle the tap and the device that is connected to the tap. This action can clear the fault in the device.
The fault reset command cannot be sent to all taps with a rung of code like the lock all and unlock all commands. By using timers, logic can be written to execute the fault reset command to all taps.
Figure 52 on page 68 shows example logic for Studio 5000. A reset command is
sent to a tap. After 3 seconds, the reset command is sent to the next tap. The process is repeated until all taps are reset.
In this example, a momentary push button is used to initiate the subroutine. The
FRC_0 output is latched; this output is for the first tap (Tap 0). The output starts a timer. The timer value is set to 3000 ms; enough time for the tap to execute its startup self-test. After timer is done, the FRC_0 output is unlatched, and the FRC_1 output is latched. The steps are repeated for each tap.
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Chapter 8 Studio 5000 Example Logix Code
Figure 52 - Jump to Fault Reset Subroutine
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Studio 5000 Example Logix Code Chapter 8
Guard Locking with Fault Reset Command
Figure 53 on page 70 shows an example of how the lock, unlock, and fault reset
commands can be used. In this example, a guard locking interlock switch (like the
TLS-ZR or 440G-LZ) is connected to tap 4. Momentary, normally open push buttons initiate the lock and unlock commands. The logic initiates the fault reset command automatically.
The safety outputs of the guard locking switch can be OFF for various reasons:
• The switch is unlocked.
• The gate is not closed.
• The switch has faulted.
If the gate is not closed and a lock command is issued to the tap, the tap and switch do not fault. If the gate is then closed, the tap does not automatically lock the gate. The operator must issue an unlock command, followed by a lock command.
The GuardLink taps only know that the safety outputs of the switch are OFF.
The example logic allows an operator to attempt to lock the switch twice. If on the third attempt, the switch does not lock, the logic automatically sends a fault reset command to the tap. The fault reset command cycles power to the switch, in an attempt to clear a faulted state. If on the fourth unsuccessful attempt to lock the switch, an inspect flag is set. This flag can be used to inform the operator to inspect the tap, the switch, and its cabling.
You can change the number of attempts and the delay that is allowed before determining the lock command does not work. The delay must be set for at least
200 ms.
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Chapter 8 Studio 5000 Example Logix Code
Figure 53 - Logix
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