FX3U-20SSC-H positioning Learning to Use the FX Family for Positioning Control
FX Positioning Control Systems 4 - 61
4.6 FX3U-20SSC-H positioning
The FX
3U(C)
PLC supports connection with the FX
3U
-20SSC-H special function block, which is an
advanced module to perform positioning operations on two axes using Mitsubishi’s fiber optic com-
munication servo network known as SSCNET III (Servo System Controller Network).
Important references for understanding positioning with the FX
3U
-20SSC-H include:
● FX
3U
-20SSC-H User’s Manual – (JY997D21301)
● FX Configurator-FP Operation Manual – (JY997D21801)
It is assumed that you will have read the above manuals or that you will have them nearby for refer-
ence.
4.6.1 Overview of control
Using an FX
3U
PLC with the FX
3U
-20SSC-H (20SSC-H) module and two Mitsubishi MR-J3-B servo ampli-
fier systems, high speed positioning with pulse output frequencies up to 50,000,000 pulses/second
(50 MHz) is possible on two axes. However, since motors compatible with the MR-J3-B servo amplifier
system have a maximum rated speed of 6,000 RPM, the maximum controllable speed from the
20SSC-H becomes:
The FX
3U
-20SSC-H provides several advantages compared to other controllers in the FX family:
With the use of a built-in Flash ROM, the FX
3U
-20SSC-H can store data permanently via non-volatile
storage. Since the flash memory transfers all of its data to the buffer memory of the 20SSC-H each time
the power is turned ON, the flash memory provides extra benefit for applications requiring a default
set of data to be automatically loaded. This eliminates the need to use a PLC program for setting
parameters and table data, which can greatly simplify the length and complexity of a ladder program.
The FX
3U
-20SSC-H includes an input connector to connect manual pulse generator dials and various
switches such as the START, DOG, and interrupt switches. These inputs assist in controlling position-
ing operations and are necessary to operate instructions such as the interrupt 1-speed constant quan-
tity feed instruction and the DOG type mechanical zero return command.
FX
3U
-20SSC-H
Feature
Advantage
Bidirectional
communication
With SSCNET III, the PLC can communicate with the servo amplifier to monitor torque, servo status
flags, servo parameters and absolute position data.
Wiring
Easy to use wiring.
High immunity to noise from external devices.
Long distance wiring (50m).
Software
Easy setup of parameters and table data (up to 300 table operations per axis).
Convenient use of monitoring and testing functions.
Tab. 4-37:
Features and advantages of FX
3U
-20SSC-H
6,000 262,144 = 26,214,400
1
60
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