Stagehand Pro 4: Sensor Input
Last updated
Last updated
The 24-pin Sensor Input receptacle includes signal inputs for the following sensors:
Limit Switches (to prevent overtravel of a machine)
Cross groove detection (to halt a winch or hoist if cable is winding improperly)
Load cell (to detect the weight being lifted by a machine)
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 |
|---|---|
1 | +24VDC |
2 | Ultimate Limit Signal |
3 | +24VDC |
4 | Reverse Limit Signal |
5 | +24VDC |
6 | Forward Limit Signal |
The Ultimate Limit signal is used as a redundant signal to halt motion if an initial Forward or Reverse Limit Switch failed to stop the machine. There is a single Ultimate Limit Signal on the Stagehand Pro 4. To protect both directions of travel, a pair of physical switches can be wired in series.
Ultimate Limit switches should be physically positioned to trigger after the initial Forward and Reverse Limit switches.
If an Ultimate Limit is activated, the Stagehand will disallow any further movement in either direction until the limit is physically cleared or the Ultimate Limit Override Button is pressed. An Ultimate Limit activation indicates a failure of an initial limit switch and must be investigated. You cannot recover from an Ultimate Limit activation by running a cue.
A Normally-Closed (N.C.) switch can be wired into the Reverse Limit input. If the limit switch is activated, the Stagehand will not allow further motion in the reverse direction until the limit is cleared by any of the following means:
moving in the forward direction far enough to clear the limit switch
adjusting the switch mechanically
pressing the Reverse Limit Override Button if it is safe to do so
A Normally-Closed (N.C.) switch can be wired into the Forward Limit input. If the limit switch is activated, the Stagehand will not allow further motion in the forward direction until the limit is cleared by any of the following means:
moving in the reverse direction far enough to clear the limit switch
adjusting the switch mechanically
pressing the Forward Limit Override Button if it is safe to do so.
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.
| Pin # | Description |
|---|---|
1 | 24VDC |
3 | 24VDC |
5 | 24VDC |
9 | Cross Groove Input |
11 | 24VDC |
The Cross Groove (X-Groove) Detection will halt all motion unless +24VDC is supplied to input pin #9. Most commonly, this signal is used on a winch or hoist to stop motion when the wire rope jumps a groove because of pulley misalignment.
To clear the Cross Groove Fault, press the Sensor Override Button and jog the machine in the opposite direction until there is no longer a cross groove.
Not every machine needs Cross Groove Detection. If your machine does not utilize Cross Groove Detection, you must jump input #9 with a +24VDC source pin to enable motion.
The Cross-Groove Detection signal does not have a dedicated voltage source pin. Instead, source the signal voltage from any of the +24VDC pins listed in the table above.
| PIn # | Description |
|---|---|
10 | Load Cell Signal - Analog Input (4-20mA) |
11 | +24VDC |
12 | COM (0VDC) |
The Load Cell Input is an analog signal to read the weight being lifted, or force exerted, by a machine. The load cell can be powered by Pins #11 & #12. Pin #10 will read a 4-20mA analog signal from the load cell. The 4-20mA signal can be scaled in Spikemark to display accurate load readings.
In addition to displaying the load, the Stagehand can be configured to halt when either the load exceeds a maximum value (Overweight Fault) or drops below a minimum value (Underweight Fault).
To clear a Load Cell Fault either:
Reduce the load (overweight)
Clear the obstruction (underweight)
Push the Sensor Override button and manually jog the motor
Underweight and Overweight Alarms can be disabled through Spikemark.
| Pin # | Description |
|---|---|
13 | Speed Encoder - A |
14 | Speed Encoder - /A |
15 | Speed Encoder - B |
16 | Speed Encoder - /B |
17 | +5VDC |
18 | COM (0VDC) |
19 | Position Encoder - A |
20 | Position Encoder - /A |
21 | Position Encoder - B |
22 | Position Encoder - /B |
23 | +5VDC |
24 | COM (0VDC) |
GND | Shield |
Stagehand Pro 4 utilizes two encoder signals. One for monitoring speed and one for positioning.
Encoder requirements:
5 VDC
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 4.
Both encoder signals can come from a single encoder by splitting the signal to both inputs.
The Speed Encoder should be directly connected to the motor. It provides feedback to the Variable Frequency Drive (VFD) to monitor overspeed faults. It also provides precise speed regulation which enables full-torque at zero-speed. This signal is used by the VFD to verify the speed of the machine closely matches the commanded speed whether running cues, or jogging manually.
The speed encoder signal is used solely by the VFD for closed-loop vector speed control. If the VFD is switched to a sensorless speed control mode, the speed encoder signal is not used.
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. Engaging the Emergency Stop will force the Stagehand to store the position to memory immediately. During normal operation, the Stagehand will wait for a calm moment in the show (when the machine hasn't moved for a few minutes) to record the position.
