Serial Output

The Serial Output sends actuator positions over a serial (COM) port. It’s designed for custom or DIY motion controllers that accept serial data — for example, Arduino-based builds, Sabertooth motor drivers, or any hardware that reads position commands from a serial port. With configurable framing, output format, and per-axis prefixes/suffixes, it can adapt to almost any serial protocol.

When to Use This

Use the Serial Output when:

You have a DIY motion controller that accepts serial data.
Your controller is not directly supported by one of the dedicated outputs (SMC3, Thanos, DMover, M4S, VNM).
You need to interface with motor drivers like Sabertooth that use a simple serial protocol.
You want full control over the byte format, framing, and encoding of position data.

Setup Steps

Connect your serial device to your PC via USB.
In DR Sim Manager, go to the Outputs tab and click the + tab.
Select Serial Output from the list.
Select your COM port and set the baud rate to match your device.
Configure parity, data bits, and stop bits if your device requires non-default values.
Set the axis count and position bits to match your controller’s protocol.
Choose the output type (Binary, Decimal, or Hexadecimal).
For each axis, set the prefix, suffix, and invert options as needed.
Optionally set startup and shutdown strings for initialization and parking commands.

Settings

Connection Settings

COM Port — The serial port your controller is connected to. Click Refresh to rescan.
Baud Rate — Communication speed, selectable from 300 to 921,600. Must match your device’s configuration.
Parity — Error-checking mode: None, Odd, or Even.
Data Bits — Number of data bits per frame: 5, 6, 7, or 8.
Stop Bits — Number of stop bits: 1, 1.5, or 2.

Output Settings

Axis Count — Number of axes to transmit (1 or more). Each axis appears as a mappable channel.
Position Bits — Resolution of each position value in bits (default: 8). Higher values give finer positioning. For example, 8-bit gives 256 positions (0–255), 16-bit gives 65,536 positions (0–65535).
Output Type — Data format for position values:
- Binary — Raw binary encoding (most compact; typical for embedded controllers).
- Decimal — ASCII decimal numbers (human-readable; e.g., “1023”).
- Hexadecimal — ASCII hex numbers (e.g., “3FF”).
Output Rate — How frequently position updates are sent, in milliseconds (default: 2 ms).

Startup & Shutdown Strings

Startup String — A byte string sent once when the output connects. Useful for initializing your controller or enabling motors.
Shutdown String — A byte string sent once when the output disconnects. Useful for parking actuators or disabling motors.

Both strings support special notation:

Hex bytes — Use 0xFF notation to send raw byte values (e.g., 0xFFFF sends two bytes: 0xFF 0xFF).
ASCII codes — Use <code> notation to send specific ASCII characters (e.g., <13> sends a carriage return, <10> sends a line feed).
Plain text — Any other characters are sent as-is.

Examples:

INIT<13><10> — Sends the text “INIT” followed by a carriage return and line feed.
0xFF0x00 — Sends two raw bytes: 0xFF and 0x00.
MOTORS_ON<13> — Sends “MOTORS_ON” followed by a carriage return.

Axis Mapping

For each axis, you can configure:

Device — The sim component to read from.
Actuator — Which actuator output to send.
Prefix — Bytes to prepend before the position value (e.g., S for Sabertooth-style protocols). Supports the same special notation as startup/shutdown strings.
Suffix — Bytes to append after the position value (e.g., <13> for a carriage return line ending). Supports the same special notation as startup/shutdown strings.
Invert — Reverse the direction of this axis (the position value is flipped so that 0 becomes the maximum and vice versa).

Building a Custom Protocol

The output constructs each packet by concatenating, for each axis: Prefix + Position Value + Suffix. All axes are combined into a single packet sent per output cycle.

Example — Sabertooth-style protocol: If your controller expects S<value><CR> for each axis, set the prefix to S and suffix to <13>.

Example — Simple binary protocol: For a controller expecting raw 16-bit binary values with no framing, set Position Bits to 16, Output Type to Binary, and leave prefix and suffix empty.

Troubleshooting

Device not responding

Check baud rate — The baud rate must match exactly between DR Sim Manager and your device. A mismatch produces garbled data or silence.
Check COM port — Verify in Device Manager > Ports (COM & LPT).
Check data bits, parity, stop bits — These must also match your device’s configuration. Most devices use 8 data bits, no parity, 1 stop bit (8N1).
Check output type — If your device expects ASCII text, use Decimal or Hexadecimal. If it expects raw bytes, use Binary.

Position values seem wrong or garbled

Verify the Position Bits setting matches what your controller firmware expects.
Check whether your controller expects big-endian or little-endian byte order. DR Sim Manager sends binary values in big-endian (most significant byte first).
If using Decimal output type, check whether your controller expects leading zeros or fixed-width strings.

Startup string not working

Use a serial terminal (like PuTTY or the Arduino Serial Monitor) to manually test your startup command and verify the device responds correctly.
Check that you’re using the correct line ending notation (e.g., <13><10> for CR+LF).

COM port not listed or “Access Denied”

See Serial Output Not Working for general COM port troubleshooting steps.