RoboteQ AX1500, AX2550 Counter Read Data Format, Encoder Testing and Setting Using the PC Utility

Models: AX2550 AX1500

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Counter Read Data Format

Counter Read Data Format

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 ahead of any number string starting with a digit value lower than 8 (i.e. 0 to 7). The table below shows examples of this scheme as applied to various counter values.

TABLE 29. Example counter values and RS232 output using a reduction scheme

Decimal

32-bit Hex

Controller Output

 

 

 

+5

00000005

5

 

 

 

+250

000000FA

0FA

 

 

 

-6

FFFFFFFA

A

 

 

 

-235

FFFFFF15

F15

 

 

 

+91,011,186

056CB872

56CB872

 

 

 

-7,986,091

FF862455

862455

 

 

 

When reading the counter value into a microcomputer, the reverse operation must take place: any output that is less than 8 digit long must be completed with a string of 0’s if the first digit is of value 0 to 7, or with a string of F’s if the first digit is of value 8 to F.

The resulting Hex representation of a signed 32-bit number must then be converted to binary or decimal as required by the application.

The burden of this extra processing is more than offset by the bandwidth relief on the con- troller’s serial port.

Encoder Testing and Setting Using the PC Utility

Extensive diagnostic, calibration, setting and testing support is provided in the Roborun PC utility. Basic instructions on how to install and run the PC utility can be found in “Using the Roborun Configuration Utility” on page 161

AX1500 Motor Controller User’s Manual

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RoboteQ AX1500, AX2550 Counter Read Data Format, Encoder Testing and Setting Using the PC Utility, Decimal, bit Hex