RoboteQ AX2550/2850 user manual RS232 Communication with the Encoder Module

RS232 Communication with the Encoder Module

Encoders do not report an absolute position value but a count that is relative to the point where the motor shaft was at power up. It is typically necessary to have the motors moved to a “home” position and reset the counters at that reference point.

RS232 Communication with the Encoder Module

The Encoder Module contains its own Microcontroller and firmware in Flash. The Encoder’s MCU communicates with the one on the main board of the controller. During normal operations, the two MCUs exchange information as needed, invisibly to the user.

During a short time, at power up, however, the Encoder’s MCU will send data to the main serial port.

The sent data is a separate prompt message which:

•Announces the presence of the encoder MCU

•Outputs its software revision and date

•Outputs a code identifying the module’s hardware ID

This information can be visualized by connecting the controller to a PC’s serial port and run- ning the Hyperterm terminal emulation software. Note that a link to a properly configured Hyperterm session is automatically installed in the Start menu when installing the Roborun utility.

The serial port settings are described in “Serial (RS-232) Controls and Operation” on page 87.

Power up prompt from main MCU

Hardware Code of main board

Power up prompt from encoder MCU

Hardware Code of Encoder Module

FIGURE 89. Hyperterm session showing power up messages from both MCUs

After this information is sent, the Encoder’s MCU will “listen” for approximately 100ms and will enter the In System Programming mode (ISP) if the letter “Z” is sent to it. While in the ISP mode, new software can be loaded into the Encoder’s MCU via the controller’s main serial port.

AX2500/2850 Motor Controller User’s Manual 141