Dual Channel Input Stop with Test and Mute (DCSTM)

This instruction applies to the Compact GuardLogix 5370, GuardLogix 5570, Compact GuardLogix 5380, and GuardLogix 5580 controllers.
The Dual Channel Input Stop with Test and Mute (DCSTM) instruction monitors dual-input safety devices whose main function is to stop safely, for example, an E-stop, light curtain, or safety gate. This instruction can only energize Output 1 when both safety inputs, Channel A and Channel B, are in the active state as determined by the Input type operand, and the correct reset actions are carried out.
In addition, this instruction can mute a safety device, such as a light curtain. When muting is enabled, a safety device sensing field can be broken, where Channel A and Channel B can go to the safe state without de-energizing Output 1. The Muting Lamp Status input is used to monitor the status of the Muting Lamp output. If this input is ever OFF (0), a fault is generated.
WARNING:
When muting a safety device, the device is no longer protecting the hazard, so some other protection must be in place.
The timing diagrams from the Dual Channel Input Stop (DCS) and Dual Channel Input Stop Test (DCST) instruction are applicable to this instruction as well.
DCSTM operation diagrams, shown below, highlight the features of the mute-related operands, such as Mute, Muting lamp Status, and Muting Lamp.
Available Languages
Ladder Diagram
DCSTM_LD_avail_v31
Function Block
This instruction is not available in function block.
Structured Text
This instruction is not available in structured text.
Operands
The DCSTM instruction requires its first operand be an instance of the DCI_STOP_TEST_MUTE data type.
IMPORTANT:
Unexpected operation may occur if:
  • Output tag operands are overwritten.
  • Members of a structure operand are overwritten.
  • Structure operands are shared by multiple instructions.
IMPORTANT:
Make sure safety input points are configured as single, not Equivalent or Complementary. These instructions provide all dual channel functionality necessary for PLd (Cat. 3) or Ple (Cat. 4) safety functions.
WARNING:
If changing instruction operands while in Run mode, accept the pending edits and cycle the controller mode from Program to Run for the changes to take effect.
The following table provides the operands that are used to configure the instruction. These operands cannot be changed at runtime.
Operand
Data Type
Format
Description
DCSTM
DCI_STOP_TEST_MUTE
tag
DCSTM structure
Safety Function
DINT
list item
This operand provides a text name for how this instruction is being used. Choices include area scanner (3), safety mat (4), light curtain (2), and user-defined (100).
This operand does not affect instruction behavior. It is for information/documentation purposes only.
Input Type
DINT
list item
This operand selects input channel behavior.
Equivalent - Active High (0):
 Inputs are in the active state when Channel A and Channel B inputs are 1.
Complementary (2):
 Inputs are in the active state when Channel A is 1 and Channel B is 0.
Discrepancy Time (ms)
DINT
immediate
The amount of time that the inputs can be in an inconsistent state before an instruction fault is generated. The inconsistent state depends on the Input Type.
Equivalent: Inconsistent state is when:
Channel A = 0 and Channel B =1, or
Channel A =1 and Channel B =0
Complementary: Inconsistent state is when:
Channel A = 0 and Channel B =0, or
Channel A =1 and Channel B =1
The range is 5...3000 ms.
Restart Type
BOOL
list item
This input configures Output 1 for either manual or automatic restart.
Manual (0): -
A transition of the reset input from OFF (0) to ON (1), while all of the Output 1 enabling conditions are met, is required to energize Output 1
Automatic (1): -
Output 1 is energized 50 ms after all of the enabling conditions are met.
Important:
 Automatic restart may only be used in application situations where no unsafe conditions can occur as a result of its use, or the reset function is being performed elsewhere in the safety circuit (for example, output function).
Cold Start Type
BOOL
list item
This operand specifies the Output 1 behavior when applying controller power or mode change to Run.
Manual (0): -
Output 1 is not energized when the Input Status becomes valid or when the Input Status fault is cleared. (The device must be tested before Output 1 can be energized.)
Automatic (1): -
Output 1 is energized immediately when the Input Status becomes valid or when the Input Status fault is cleared and both inputs are in their active state.
Test Type
DINT
list item
The operand defines which type of test occurs when Test Request transitions from ON (1) to OFF (0).
None (0): -
Turns the testing feature OFF (0).
Manual (1): -
Output 1 is de-energized immediately when Test Request input transitions from ON (1) to OFF (0). The Test Command output is energized until a functional test is carried out, such as an open and close safety gate, break and clear light curtain, and reset actions are carried out depending on the setting of the Restart Type operand.
Active (2): -
Output 1 remains energized when the Test Request input transitions from ON (1) to OFF (0) and the Test Command output is energized, which should force an automatic test of the safety device. For example, a light curtain that has test capability. If the Channel A and Channel B outputs correctly transition to the safe state and back to the active state before Test Time expires, the Test Command output is de-energized and the safety device continues normal operation. If the safety inputs do not correctly transition before Test Time expires, Output 1 is de-energized immediately and a fault is generated.
Test Time
DINT
immediate
The maximum time for an active test to complete. If the test does not complete within this time, a fault is generated. Refer to the Test Type operand for more information.
Important:
This time cannot exceed 150 ms for type-2 light curtains as specified by EN-61496-1.
The valid range is 5...1000 ms.
The following table explains instruction inputs. The inputs may be field device signals from input devices or derived from user logic.
Operand
DataType
Format
Description
Channel A
1
BOOL
tag
This input is one of the two safety inputs to the instruction.
Channel B
1
BOOL
tag
This input is one of the two safety inputs to the instruction.
Test Request
BOOL
tag
This signal forces a functional test to occur. See the Test Type operand for more information.
ON (1) -> OFF (0): Triggers a functional test.
Mute
BOOL
tag
This input is used to mute the safety device.
OFF (0): Mute is not activated.
ON (1): Mute is activated. The Muting Lamp output is energized and Output 1 is not de-energized when the safety device is tripped (Channel A or Channel B enters the safe state).
Muting Lamp Status
BOOL
tag
immediate
This is the status of the muting lamp. If this status is not valid, Output 1 is de-energized immediately and a fault is generated.
OFF (0): The Muting Lamp Status is invalid. A fault is generated.
ON (1): The Muting Lamp Status is valid.
Input Status
BOOL
tag
immediate
If instruction inputs are from a safety I/O module, this is the status from the I/O module (Connection Status or Combined Status). If instruction inputs are derived from internal logic, it is the application programmer’s responsibility to determine the conditions.
ON (1): The inputs to this instruction are valid.
OFF (0): The inputs to this instruction are invalid.
Reset
2
BOOL
tag
If Restart Type = Manual, this input is used to energize Output 1 once Channel A and Channel B are both in the active state.
If Restart Type = Automatic, this input is not used to energize Output 1.
This input clears instruction and circuit faults provided the fault condition is not present.
OFF (0) -> ON (1): The FP (Fault Present) and Fault Code outputs are reset.
1 If this input is from a
Guard I/O
 input module, make sure that the input is configured as single, not Equivalent or Complementary.
2 ISO 13849-1 stipulates instruction reset function must occur on falling edge signals. to comply with ISO 13849-1 requirements, add the logic immediately before this instruction. Rename Reset_Signal tag in this example to the reset signal tag name. Then use the OSF instruction Output Bit tag as the reset source of the instruction.
Reset_Signal Example_v31
This table explains instruction outputs. The outputs may be external tags (safety output modules) or internal tags for use in other logic routines.
Operand
Data Type
Description
Output 1 (O1)
BOOL
This output is energized when the input conditions have been satisfied.
The output becomes de-energized when:
  • Either Channel A or Channel B transitions to the safe state.
  • The Input Status input is OFF (0).
  • A manual test is requested (Test Request turns OFF (0) when Test Type = Manual).
  • An Active Test fault occurs (the Active Test does not complete within the Active Test Time).
  • The Mute input transitions from ON (1) to OFF (0) when Channel A or Channel B is in the safe state.
  • The Muting Lamp Status input is OFF (0).
Test Command (TC)
BOOL
If Test Type = Manual, this output is energized when a manual functional test must be carried out.
If Test Type = Active, this output is energized to notify a safety device, such as light curtain, that an automatic test should be carried out.
Muting Lamp (ML)
BOOL
This output is intended to drive a muting lamp
1
. The status of the muting lamp should be fed into the Muting Lamp Status input.
ON (1): Muting is currently active. The Muting Lamp is turned ON (1).
OFF (0): Muting is not currently active.
Safe state (SS)
BOOL
This output turns ON (1) when the inputs are in a safe state regardless of whether the instruction is muted or not.
ON (1): The inputs are currently in the safe state
OFF (0): The inputs are not currently in the safe state.
Fault Present (FP)
BOOL
ON (1): A fault is present in the instruction.
OFF (0): This instruction is operating normally.
Fault Code
DINT
This output indicates the type of fault that occurred. See the Fault Codes section for a list of fault codes.
This operand is not safety-related.
Diagnostic Code
DINT
This output indicates the diagnostic status of the instruction. See the Diagnostic Codes section for a list of diagnostic codes.
This operand is not safety-related.
1
Guard I/O
 module test outputs that are configured for muting can be used for this purpose.
IMPORTANT:
Do not write to any instruction output tag under any circumstances.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Index Through Arrays for array-indexing faults.
Execution
Condition/State
Action Taken
Prescan
Same as Rung-condition-in is false.
Rung-condition-in is false
The .O1, .TC, .ML, .SS and .FP are cleared to false.
Rung-condition-in is true
The instruction executes as described in the Operation section.
Postscan
Same as Rung-condition-in is false.
Operation
Normal
The timing diagram illustrates the normal muting behavior. At (A), the Muting Lamp output is energized when the Mute input turns ON (1). At (B), Output 1 is not de-energized because the instruction is currently muted. At (C), muting is turned OFF (0) but Output 1 remains energized because the safety inputs are now in the active state. At (D), Output 1 is de-energized because safety inputs transition to the safe state and muting is no longer turned ON (1). At (E), muting is activated again, but does not energize Output 1 because the mute signal is never allowed to energize Output 1. At (F), Output 1 is energized 50 ms after the safety inputs enter the active state. At (G), Output 1 is de-energized when muting is disabled and the safety inputs are in the safe state.
DCTSM Normal Operation
Muting Lamp Status Fault Operation
The timing diagram illustrates the Muting Lamp Status fault. At (A), the safety inputs enter the safe state, but Output 1 remains energized because the instruction is muted.
At (B), the Muting Lamp Status input transitions to an invalid state, which immediately de-energizes Output 1 and generates a fault. At (C), the fault cannot be reset because the Muting Lamp Status is still invalid. At (D), the fault is cleared because a reset is triggered and the Muting Lamp Status is now valid. This also energizes Output 1 because the safety inputs are in the active state.
Dual DCTSM Muting Lamp Status Fault Operation
False Rung State Behavior
When the instruction is executed on a false rung, all instruction outputs are de-energized.
Fault Codes and Corrective Actions
The fault codes are listed in hexadecimal format followed by decimal format.
Fault Code
Description
Corrective Action
0
No fault.
None.
1
The Muting Lamp Status transitioned to an invalid state while the instruction was running.
  • Check the status of the Mute input.
  • Reset the fault.
16#20
32
The Input Status input transitioned from ON (1) to OFF (0) while the instruction was executing.
  • Check the I/O module connection or the internal logic used to source input status.
  • Reset the fault.
16#4000
16384
Channel A and Channel B were in an inconsistent state for longer than the Discrepancy Time. At the time of the fault, Channel A was in the active state. Channel B was in the safe state.
  • Check the wiring.
  • Perform a functional test of the device (put Channel A and Channel B in a safe state).
  • Reset the fault.
16#4001
16385
Channel A and Channel B were in an inconsistent state for longer than the Discrepancy Time. At the time of the fault, Channel A was in the safe state. Channel B was in the active state.
16#4002
16386
Channel A went to the safe state and back to the active state while Channel B remained active.
16#4003
16387
Channel B went to the safe state and back to the active state while Channel A remained active.
16#4030
16432
The Active test did not complete within the Test Time.
  • Check the device.
  • Make sure the test feature is working properly.
  • Reset the fault.
Diagnostic Codes and Corrective Actions
The diagnostic codes are listed in hexadecimal format followed by decimal format.
Diagnostic Code
Description
Corrective Action
0
No fault.
None.
5
The Reset input is held ON (1)
Set the Reset input to OFF (0)
16#20
32
The Input Status was OFF(0) when the instruction started.
Check the I/O module connection or the internal logic used to source input status.
16#4000
16384
The device was not functionally tested at startup.
Perform a functional test of the inputs (put Channel A and Channel B in a safe state).
16#4001
16385
The device was not functionally tested after a fault occurred.
  • Check the wiring.
  • Perform a functional test of the device (put Channel A and Channel B in a safe state).
16#4030
16432
Waiting for the manual functional test to occur.
Perform a functional test of the device (put Channel A and Channel B in a safe state).
16#4031
16433
The Active test is in progress.
Information only.
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