Servotronix CDHD Series, Application Note

Page: 7 / 17

Pulse and Direction Using Single-Ended Signal Overview
Application Note 7
1 Overview
The CDHD’s Pulse and Direction Using Single-Ended Signal feature enables
the connection of PLCs with a 24 VDC single-end signal to the CDHD.
The following diagram shows how the feature is implemented.
CDHD
∑
Current
Loop
M
+
-
PE
Load
ICMD
Current
Command
HDC
Pulse and
Direction
Position
Command
Feedback
PLC
PCMD
Position
Command
PFB
Gear Block
The drive accepts an input pulse train in which the rising edge of each pulse
increments (or decrements, depending on the direction) the external input
position counter (HWPEXT) of the drive by one position count. This counter value
is passed through a gearing block and becomes the position command for the
motor.
The position command is compared to the actual motor position (PFB) to
determine the position error (PE). The drive corrects the position error by
incrementing the motor to the commanded position.
Gearing sets up a relationship between the number of input pulses (HWPEXT
counts) and the position increments of the motor shaft (or actual motor position,
PFB). The rate at which position increments of the motor shaft (motor speed)
occur is determined by the gearing relationship and the line frequency of the
pulse train.
This application note describes the pulse following capability of the CDHD
system, using Operation Mode 4-Position Gear Mode . In this type of position
control, the drive is synchronized to a master input command signal in the form
of a pulse train.
The drive is configured to read this input signal as an pulse/direction counter.
The pulse train is geared to the incremental movement of the motor shaft
through the drive’s electronic gearing block.
The drive’s homing capabilities remain available in this configuration. For more
information on homing, refer to the CDHD User Manual.