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Functions for Servo Drivers Compatible with Absolute Encoders Section 7-7
7-7-10 Overview of Absolute Encoder Output Data Acquire
Behavior of the Servo
Driver Compatible
with an Absolute
Encoder
The SEN signal being turned ON, the Servo Driver behaves in the following
manner:
1,2,3... 1. The Servo Driver transmits the state of the absolute encoder when the
SEN signal is turned ON.
The operation proceeds in the following order:
a. Transmits the multi-turn data (how many revolutions the axis of the ro-
tary encoder made) with the serial communications.
b. Transmits the initial incremental pulse (difference between present po-
sition and origin) with phase differential pulse output.
2. After transmitting the absolute value data, transmits the pulse train corre-
sponding to the rotational displacement. (Transmits the same pulse as an
incremental encoder)
Absolute Encoder
Output Data
Acquiring Method
Use the following procedure to read the absolute encoder output data from a
Servo Driver to the Motion Control Module:
Step 1 (Required): Setting Setting the Pulse Input Method
Set the pulse input method in the System Setup. Select one of the following 5
methods:
Phase differential
×1, ×2, or ×4, increment/decrement pulse input, or pulse +
direction. Set the pulse input method to a phase differential input.
Setting the Input Pulse Counting Speed
Set the input pulse counting speed to 500 kHz. To do so, set the input pulse
counting speed to 500 kHz in the System Setup.
Setting the Counter Operation
Set the Counter 1 Counter operation in the System Setup. Select one of the
following three counter operations for counting the encoder output.
• Absolute linear (CW
−) counter
• Absolute linear (CW+) counter
• Absolute circular counter
Be sure to set the System Setup’s Counter 1 Counter operation so that it
agrees with the Servo Driver’s reverse rotation mode setting.
Setting the Absolute Encoder Resolution
Set absolute encoder resolution, which is the number of pulses received from
the Servo Driver for each revolution of the encoder.
Consider both the Servo Driver's encoder dividing rate setting and the Motion
Control Module's pulse input multiplier setting (with the System Setup’s pulse
input method setting). For example, set the resolution to FA0 (4,000) when the
Servo Driver’s rate is 1,000 and the Motion Control Module’s multiplier is
×4.
Step 2 (Required):
Acquiring the Encoder
Status when the SEN
Signal is Turned ON
Turn ON the Absolute Number of Rotations Read Bit (A610.07) from the lad-
der program. At this point, the SEN signal will go ON (high level). Leave the
SEN signal ON during operation, just like the RUN signal.