RoboteQ AX2550/2850 RS232 Encoder Command Set, Read Encoder Counter, ?q or Q n, ?Q0, ?Q5

Installing, Connecting and Using the Encoder Mod-

Details on software updating is given in section Figure , “Updating the Encoder Software,” on page 152.

RS232 Encoder Command Set

The Encoder module responds to a dedicated set of commands and queries.

The serial port setting and basic command format is identical to this for all other functions of the controller, as described in “Serial (RS-232) Controls and Operation” on page 87.

Read Encoder Counter

Description:

Read the value of the Encoder counter(s). The number is a signed 32 bit number that may range from -2,147,836,648 to +2,147,836,647. The value is output in Hexadecimal format of value 80000000 to 7FFFFFFF respectively. To speed up communication, only the signifi- cant digits are sent in response to a counter query. For example, if the counter contains the value +5 (which is the same number in decimal and hex), the response to the query will be 5 and not 00000005. The formatting algorithm takes into account the number’s sign. Details on the data format is given in section

Counters’ values can be read as Absolute or Relative. An Absolute counter read will return the full counter value after every read query. In a Relative counter read, the counter value is immediately cleared immediately after it is read so that the next read query returns the new number of counts since the last time the counter was read.

Additionally, in a couple of the query modes, the Encoder module returns the sum for both counters. This is useful for measuring the average travelled distance by the right and left wheels of a robotic vehicle.

Syntax:	?q or Qn
Where n=	0: Encoder 1, Absolute
	1: Encoder 2, Absolute
	2: Sum of Encoders 1 and 2, Absolute
	4: Encoder 1, Relative
	5: Encoder 2, Relative
	6: Sum of Encoders 1 and 2, Relative
Reply:	nnnnnnnn
Where:	nnnnnnnn = counter value using 1 to 8 Hex digits. See “Counter Read
	Data Format” on page 149 for format description
Examples:
?Q0	Read Encoder 1, Absolute
?Q5	Read Encoder 2, Relative

142 AX2500/2850 Motor Controller User’s Manual Version 1.7. February 1, 2005