Two Sensor Asymmetrical Muting (TSAM)

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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Ladder Diagram

Function Block

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Two Sensor Asymmetrical Muting Application

Two Sensor Asymmetrical Muting uses two muting sensors arranged asymmetrically on either side of the light curtain. Their sensors intersect 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 function 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 your reset signal tag name. Then use the OSF instruction Output Bit tag as the instruction's reset source.

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 and the light curtain in their ON (1) state, which 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). At (B), the material blocks Sensor 1, starting the S1-S2 timer. At (C), the material blocks Sensor 2 within the S1-S2 Time period, so the S1-S2 timer stops. The S2-LC and Maximum Mute timers start. The Muting Lamp output turns ON (1), indicating that muting is enabled. At (D), the material blocks the Light Curtain within the S2-LC Time period, so the S2-LC timer stops. From (D) to (E), Output 1 remains energized while the material passes through the Light Curtain. At (E), the material clears the Light Curtain, starting the LC-S2 timer. At (F), the material clears Sensor 2 within the S2-LC and Maximum Mute time periods, so both timers stop. The S2-S1 timer starts and the Muting Lamp output turns OFF (0), indicating that muting is disabled. At (G), the material clears Sensor 1, stopping the S2-S1 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), Sensor 1 and Sensor 2 are simultaneously blocked, causing Output 1 to be de-energized and the Fault Present and Clear Area outputs to turn ON (1). The override feature can be used to clear the material from the light curtain sensing field and de-energize the Clear Area output.

Tolerated Sequence

The Two-sensor Asymmetrical Muting (TSAM) 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 1 turns OFF (0), starting the S1-S2 timer. Sensor 1 turns ON at (C), stopping the S1-S2 timer. At (D), the material completely blocks Sensor 1, turning it OFF (0), and the normal muting sequence continues. A sensor can glitch, as illustrated from (B) to (C), as a result of overtravel or load vibration. As s long as the final input sequence is valid, muting function will be allowed to 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, turning it OFF (0) and starting the S1-S2 timer. At (C), the material blocks Sensor 2 within the S1-S2 time period so the S1-S2 timer stops and the S2-LC timer starts. Because the Enable Mute input is OFF (0), muting is disabled and the Muting Lamp output remains OFF (0). 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 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 is turned 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

Sensor Input Pattern Fault Codes

Normal and Tolerated Muting Sequences

Muting Sequence Fault Codes

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 and Corrective Actions

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