Red Lion GEMINI 33 - Manual (Page 11)

PROGRAMMING INSTRUCTIONS FOR THE GEMINI 3300 BATCH COUNTER
The first part of this section provides detailed descriptions of the function
command codes for Input response modes, reset modes, output termination
modes, etc. Then, using an actual application example, the programming
instructions are “walked through” to give the user a full understanding of the
Gemini 3300 programming procedure. The descriptions below give the
function command code first, followed by the individual mode identifier. The
Function Command Summary in Appendix “D”, lists all codes.
CODE 41 - FACTORY SETTINGS
When Code 41 is called up, the unit will display a 1 as the mode. Entering a
“-” sign in front of the mode will cause the unit to re-load the factory settings
as shown in the “Factory Settings” section.
CODE 43 - INPUTS A & B RESPONSE MODES
The Gemini 3300 has six different input response modes that will directly
affect the Process Counter and the Total Counter. They are: Count (A) with
Inhibit (B); Count (A) with Up/Down Control (B); Two input
anti-coincidence Add (A)/Subtract (B); Two input anti-coincidence Add
(A)/Add (B); Quadrature; and Quadrature x4.
[43 1] COUNT WITH INHIBIT - Input A serves as the count. Input B serves
as the Inhibit input. When Input B is low, the counter will ignore the count
signal appearing at Input A. When Input B is at a high level, the signal
appearing on Input A will be counted. The “Process Counter Reset Action
Modes” will determine the count direction for the Process Counter. In
applications where the Inhibit function is not actually used, the Input B
“SRC/SNK” position of the “INPUT CONFIGURATION DIP SWITCH”
should be set to the “SNK” position to provide a 7.8 Kohm pull-up resistor.
This will set Input B to the Non-Inhibit state.
[43 2] COUNT WITH UP/DOWN CONTROL - In this mode, count direction
can be controlled by the second input. Input A serves as the count input and
Input B serves as the direction control signal input.
When Input B is at a high level, the counter will count up. When Input B is
at a low level, the counter will count down.
[43 3] TWO INPUT ANTI-COINCIDENCE ADD/SUBTRACT - This mode
effectively separates count pulses which may simultaneously appear at the
two inputs. The Gemini unit processes the count pulses into a string of
time-separated pulses, so the internal counter will not lose any count
pulses. Input A serves as the add input (count increments) and Input B
serves as the subtract input (count decrements).
[43 4] TWO INPUT ANTI-COINCIDENCE SUMMING - Input A and B are
summed or added in the same manner as above. This mode is
uni-directional. The “Process Counter Reset Action Modes”, will
determine the count direction for the Process Counter.
[43 5] QUADRATURE COUNTING - Quadrature counting modes are
primarily used in positioning and anti-jitter applications. The reason this
mode works is due to the manner in which two pickups are positioned
relative to each other. The signal on Input B is a pulse train signal shifted
90° away from the Input A signal. These two signals are processed by the
Gemini as follows:
Input A serves as the count, while Input B serves as the quadrature input.
For quadrature with single edge counting, the counter will count in a
positive direction when Input A is a negative going edge and Input B is at a
low level. The counter will count in a negative direction when Input A is a
positive going edge and Input B is at a low level. All transitions on Input A
are ignored when Input B is at a high level. These logic rules provide the
basis for anti-jitter operation which will prevent false counts from
occurring due to back-lash, vibration, chatter, etc.
When two edge counting is used, the quadrature mode works the same as
with single edge counting when Input B is low. But when Input B is at a
high level, counts at Input A are no longer ignored. Instead the logic rules
for Input A are complemented, allowing both edges of Input A to be
counted. This doubles the effective resolution of the encoded input.
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