Stagehand Apprentice 2: Sensor Input

The Signal Cable is shared between the Stagehand Apprentice and Stagehand Pro controllers, although the Stagehand Apprentice doesn't utilize all of the inputs.

Pins 7 thru 18 are not connected on the Stagehand Apprentice.

The 24-pin Sensor Input receptacle includes signal inputs for the following sensors on the Stagehand Apprentice:

• Limit Switches (to prevent overtravel of a machine)

  • Reverse

  • Forward

• Encoder signal

Limits

Limit signals are designed as fail-safe inputs. To allow movement in the corresponding direction, an electrical signal must be present. If the signal is interrupted, motion will stop. Limit switches should be wired Normally-Closed (N.C.) for failsafe operation.

Pin #	Description
3	+24VDC
4	Reverse Limit Signal
5	+24VDC
6	Forward Limit Signal

Reverse Limit

Forward Limit

A Normally Closed (N.C.) switch can be wired into either the Forward or Reverse Limit inputs. If the limit switch is activated, the Stagehand will not allow further motion in the whatever direction the limit is struck until the limit is cleared by any of the following means:

• moving in the opposite direction far enough to clear the limit switch

• adjusting the switch mechanically

• pressing the Forward or Reverse Limit Override Button if it is safe to do so

Common Wiring - Alternate

Each signal pair has a voltage source pin and a signal pin. The voltage sourcing pins (indicated as +24V on the diagram above) are all equivalent and are distributed for convenience. They can be wired in pairs, or a single source pin can be used to reduce conductor count.

Alternate Wiring To Reduce Conductor Count

Encoder

Pin #	Description
19	Position Encoder - A
20	Position Encoder - /A
21	Position Encoder - B
22	Position Encoder - /B
23	+12VDC
24	COM (0VDC)
GND	Shield

The Stagehand Apprentice 2 only uses a single encoder.

Encoder requirements:

• 12VDC tolerant

• Incremental quadrature encoder signal

• Differential line drivers: A, /A, B, /B

Z and /Z index pulses are not used, but encoders with those signals are compatible with the Stagehand Pro 5.

The Position Encoder provides feedback to the Stagehand Card to track the position of the machine or scenery. It is actively used to run cues, and it is constantly monitored to track the position of the machinery or scenery at all times. However, it is not actively used during manual operation (aka jogging). This allows for manual operation in case of a position encoder failure.

Position information is stored in the Stagehand's memory so it remembers the location of the machine during a loss of power. We call this Persistent Position. The Persistent Position data is written to the Stagehand Apprentice 2 every 500ms.