Two-sensor Symmetrical Muting (TSSM)

This instruction provides a temporary, automatic disabling of the protective function of a light curtain, which allows material to be transported through the light curtain sensing field without stopping the machine. Muting sensors differentiate between materials and personnel, and must act together along with the light curtain, in a specific switching sequence when the appropriate material passes the sensing field.

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Two Sensor Symmetrical Muting Application

Two Sensor Symmetrical Muting uses two muting sensors arranged symmetrically on either side of the light curtain. Their sensors intersect at or just behind the light curtain in the center of the protected opening.

Operands

This table provides the parameters for this instruction. The parameters cannot be changed at runtime.

This table provides the input parameters for this instruction.

1

ISO 13849-1 stipulates instruction reset functions must occur on falling edge signals. To comply with ISO 13849-1 requirements, add this logic immediately before this instruction. Rename the Reset_Signal tag in this example to reset your signal tag name. Then use the OSF Instruction Bit tag as the reset source for the instruction.

This table provides the output parameters for this instruction.

Operation

Normal Operation

One sequence of muting sensor and light-curtain input transitions lets the protective function of the light curtain be disabled (muted). That sequence must start with both of the muting sensors (S1, S2) and the light curtain in their ON (1) state. This indicates that the light-curtain sensing field is clear of all personnel and material.

At (A), the Sensors and the Light Curtain are cleared and the Output 1 output is energized when the Reset input turns ON (1). The material blocks Sensor 1 at (B), starting the S1S2 Discrepancy timer. At (C), the material blocks Sensor 2, stopping the S1S2 Discrepancy timer and starting the S1S2-LC Minimum, the S1S2-LC Maximum, and the Maximum Mute timers. At (D), the S1S2-LC Minimum time period expires, starting the Maximum Mute timer and turning the Muting Lamp output ON (1). At (E), the material blocks the Light Curtain within the S1S2-LC Maximum time period, stopping the S1S2-LC Maximum timer. From (E) to (F), Output 1 remains energized while the material passes through the Light Curtain. At (F), the material clears the Light Curtain and the S1S2-LC Minimum timer starts. At (G), the S1S2-LC Minimum time period expires. The Muting Lamp output turns OFF (0) and the Maximum Mute timer is stopped, indicating that muting is disabled. The material clears Sensor 2 at (H), starting the S1S2 Discrepancy timer. At (I), the material clears Sensor 1 within the S1S2-LC Maximum time period, stopping the S1S2 Discrepancy timer.

Invalid Sequence

Any input sequence other than the normal operation sequence results in Output 1 being de-energized.

At (A), Output 1 is energized just as in a normal sequence of operation. At (B), the material blocks Sensor 1, starting the S1S2 Discrepancy timer. The material blocks Sensor 2 at (C), stopping the S1S2 Discrepancy timer, starting the S1S2-LC Minimum timer and the S1S2 -LC Maximum timer. At (D), the Light Curtain is blocked during the S1S2-LC Minimum Time period, causing Output 1 to be de-energized. The S1S2-LC Maximum timer stops.

Tolerated Sequence

The Two-sensor Symmetrical Muting (TSSM) instruction tolerates application dynamics that might cause an input to oscillate due to over-travel or load vibration.

At (A), Output 1 is energized just as in a normal sequence of operation. At (B), Sensor 2 turns OFF (0), starting the S1S2 Discrepancy timer. Sensor 2 turns ON (1) at (C), stopping the S1S2 Discrepancy timer. At (D), the material completely blocks Sensor 2, turning it OFF (0), and the normal muting sequence continues. A sensor may glitch, as illustrated from (B) to (C), as a result of over-travel or load vibration. As long as the final input sequence is valid, the instruction lets the muting function occur.

Dangerous Portion of Cycle

The Enable Mute input enables or disables the protective function of the light curtain. When the Enable Mute input is OFF (0), the protective function of the light curtain is enabled and material may not pass through the light curtain sensing field.

At (A), Output 1 is energized just as in a normal sequence of operation. At (B), the material blocks Sensor 1 and Sensor 2, turning them OFF (0) and starting the S1S2-LC Minimum, the S1S2-LC Maximum, and the Maximum Mute timers. Because the Enable Mute input is OFF (0), muting is disabled and the Muting Lamp output remains OFF (0). At (C), the S1S2-LC Minimum time period expires. The material blocks the Light Curtain at (D), and Output 1 is de-energized.

If the application does not have parts of its cycle where it is unacceptable for material to pass through the light curtain, you can disable this feature by setting the Enable Mute input to a constant value of ON (1).

Override Operation

The override feature lets an operator manually energize Output 1 so that material can be cleared from the light curtain sensing field.

At (A), the Override input turns ON (1). Output 1 is energized and the Maximum Override timer starts. At (B), the material clears Sensor 1 and the Clear Area output turns OFF (0). At (C), the Override input turns OFF (0) within the Maximum Override time period. Output 1 is de-energized and the Maximum Override timer stops.

False Rung State Behavior

When the instruction is executed on a false rung, all instruction outputs are de-energized.

Fault Codes

The fault codes are listed in hexadecimal format followed by decimal format.

General Fault Codes

Input Pattern Fault Codes

Muting Sequence Faults

To correct an invalid sequence fault, check the alignment of the sensors with regard to the material being moved and the system timing and then reset the fault.

Correcting Invalid Sequence Faults

Diagnostic Codes

The diagnostic codes are listed in hexadecimal format followed by decimal format.

Affects Math Status Flags

No

Major / Minor Faults

None specific to this instruction. See

Index Through Arrays

for array-indexing faults.

Execution