PR Series Stepper Drive RS485 Communication Operation Example Code

1. Initial Connection and Establishing Communication

Prerequisites

• A PR series stepper drive with the motor and power cables connected;
• An RJ45 Ethernet cable;
• An RS485-to-USB converter cable (If you are unsure which one to choose, we recommend using our product: https://www.omc-stepperonline.com/1-5m-59-06-usb-to-rs422-rs485-serial-port-converter-adapter-cable-rs485-1);
• A serial port software or controller capable of sending RS485 commands.

Wiring

Find the definition of the RS485 interface in the PR series stepper drive manual as follows:

Compare with the pinout of the RJ45 Ethernet cable:

It can be seen that we need to select wires 1, 2, and 5 to connect to the RS485-to-USB converter cable. For the RJ45 Ethernet cable, keep one end with the RJ45 connector to plug into the drive's CN3 port. Cut off the connector at the other end, strip wires 1, 2, and 5 (brown, brown-white, and blue), and connect them in the following order:

485+ ----------------TXD+

485- ----------------TXD-

GND ---------------GND

After wiring, insert both ends into the drive and PC interfaces respectively. Power on the drive and open the serial port software to establish communication. (If communication fails to establish, please refer to this troubleshooting article:

Note:

Before entering the code, set SW1 to ON and SW2-5 to OFF! This sets the RS485 address to 01.

If you need to save the written RS485 command, write the following as the last command:

01 06 00 2D 00 42 CRC CRC

Otherwise, the written parameters will revert to their default values after the drive is powered off!

When using speed mode, after saving and restarting the drive, you must re-enter a start command. The motor will not rotate immediately upon power-up.

2. Operation Modes

2.1. Speed Control Mode

Please note the following:

Take the command 01 06 00 2D 00 12 CRC CRC as an example:

• 01 is the axis address (set SW1 to ON, SW2-5 to OFF).
• 06 is the write command.
• 00 2D is the parameter address to write to.
• 00 12 is the value to write.

• CRC CRC is the checksum.

Some serial port tools may not require a checksum, while others may require manual calculation. Please pay attention to this.

Sometimes, multiple registers can be written with a single command. For example, the content from line 2 to line 4 in the above code can be represented as:

01 10 00 1D 00 03 06 00 3C 00 64 00 64 CRC CRC

• 01 is the axis address (default is 1).
• 10 is the command to write multiple registers.
• 00 1D is the starting parameter address (subsequent addresses follow sequentially after two bytes).
• 00 03 06 indicates the number of parameters and bytes to write.
• 00 3C is the value for the rotation speed.
• 00 64 is the value for acceleration/deceleration time.
• CRC CRC is the checksum.

2.2. Multi-Speed Operation

Note:

Some drive peripherals only support X0 to X3, totaling 4 input signals. Therefore, position segment selection supports up to 8 segments at most.

2.3. Absolute Position Movement of 5000 pulses(Default setting: 10000 pulses/rev)

Note:

It is important to note that if the total pulse quantity you set is less than the minimum pulse quantity calculated based on the acceleration/deceleration time and maximum speed, the drive will not reach the maximum speed you configured.

2.4. Multi-Position Operation under Absolute Positioning(First segment: 1000 pulses; Second segment: 5000 pulses)

Note: In this mode, the first segment moves from the origin (0) to the position of 1 revolution, and the second segment moves an additional 5 revolutions relative to the first segment.

In multi-segment mode, the 0x0050 Relative/Absolute Position Register controls whether each position segment operates in relative or absolute positioning mode.

Note:

* When using PIN terminals for segment selection, the signal must remain valid for 5ms before and 5ms after the "PT trigger signal".

* Some drive peripherals only support X0 to X3 where 4 input signals in total, so the position segment selection supports up to 8 segments at most.

3. Common Commands

Motor Enable:

01 06 00 2D 00 12 CRC CRC

Motor Disable:

01 06 00 2D 00 11 CRC CRC

Restore Factory Settings:

01 06 00 2D 00 41 CRC CRC

Save All Parameters:

01 06 00 2D 00 42 CRC CRC

Stop Command:

01 06 00 27 01 00 CRC CRC

Emergency Stop Command:

01 06 00 27 02 00 CRC CRC

Motor Maximum Effective Current 150mA:

01 06 01 02 05 DC CRC CRC

Updated on: 26/08/2025