> For the complete documentation index, see [llms.txt](https://docs.creativeconners.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.creativeconners.com/docs/stagehand/stagehand-apprentice-2/stagehand-apprentice-2-making-the-connections/stagehand-apprentice-2-sensor-input.md).
# 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.
{% hint style="info" %}
Pins 7 thru 18 are not connected on the Stagehand Apprentice.
{% endhint %}
The 24-pin **Sensor Input** receptacle includes signal inputs for the following sensors on the Stagehand Apprentice:
* [Limit Switches](#limits) *(to prevent overtravel of a machine)*
* [Reverse](#reverse-limits)
* [Forward](#forward-and)
* [Encoder signal](#encoders)
## 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
{% hint style="info" %}
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.
{% endhint %}
## 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
{% hint style="info" %}
Z and /Z index pulses are not used, but encoders with those signals are compatible with the Stagehand Pro 5.
{% endhint %}
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.
{% hint style="info" %}
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.
{% endhint %}
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.creativeconners.com/docs/stagehand/stagehand-apprentice-2/stagehand-apprentice-2-making-the-connections/stagehand-apprentice-2-sensor-input.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.