RoboteQ AX3500 Counter Read Data Format, RC Pulse Outputs Activation, Address *A5 to *AF, Size

Counter Read Data Format

RC Pulse Outputs Activation

Address: *A5 to *AF

The AX3500 has 8 pulse output for commanding standard RC servos or additional control- lers. The pulse width for every channel can only be changed using simple RS232 com- mands. Reading and changing the pulse width is done by accessing 8 parameters that are stored in the Encoder’s module MCU RAM. Parameter address and returned values are two digit Hexadecimal numbers (8-bit).

The table below lists maps the RC registers that can be accessed using this command.

TABLE 32. RC Pulse Ouput Register

Address	RC Channel	Default Value	Size	Access
*A8	RC Channel 1	Hex 7F (dec 127)	1 byte	Read/Write
*A9	RC Channel 2	Hex 7F (dec 127)	1 byte	Read/Write
*AA	RC Channel 3	Hex 7F (dec 127)	1 byte	Read/Write
*AB	RC Channel 4	Hex 7F (dec 127)	1 byte	Read/Write
*AC	RC Channel 5	Hex 7F (dec 127)	1 byte	Read/Write
*AD	RC Channel 6	Hex 7F (dec 127)	1 byte	Read/Write
*AE	RC Channel 7	Hex 7F (dec 127)	1 byte	Read/Write
*AF	RC Channel 8	Hex 7F (dec 127)	1 byte	Read/Write

Counter Read Data Format

When receiving a counter read query, the encoder module will output the value of its 32-bit counter. If all 32-bit are sent, this would require 8 ASCII digits to represent the value.

A 32-bit counter can store over 2 billion counts in each direction. In practice, it will be rare that counts will be so large than only a partial number of the counter’s bits will be signifi- cant at any given time.

In order to create a more efficient data stream on the controller’s serial port, a simple com- pression technique is implemented. The scheme eliminates all of the counter’s most signif- icant bits if they are at 0 (for a positive count number) or F (for a negative count number).

For example, if the counter value is Hex 00000015, the value 15 will be returned after a counter query.

For negative numbers, a count value of -5 (which is FFFFFFFB in hex), the response to the query will be B.

To distinguish between positive and negative numbers, the Encoder module will insert a 0 ahead of any number string starting with a digit value higher than 7 (i.e. 8 to F) to signify that the number is positive. For negative numbers, the Encoder module will insert an F

AX3500 Motor Controller User’s Manual 167