Rockwell Automation 1771-QB Linear Pos. - Manual (Page 54)

Installing the Linear Positioning Module
Chapter 5
5Ć15
ATTENTION: In servo valve control systems, axis drift may occur
due to imprecise valve nulling even with zero analog output. It is
recommended that emergency stop switches, such as overtravel limit
switches, also turn off axis power and close a blocking valve
installed between the servo valve and the prime mover.
Important: If you have enabled the discrete inputs via the parameter block,
don’t leave the hardware stop terminals disconnected–you must connect them to
a source which is normally high. If the connection breaks, the input goes low
and axis movement automatically stops.
ATTENTION: Use the hardware stop to disable the servo valve
drive or stop axis motion only in an emergency. Abruptly stopping
axis motion places mechanical stress on the positioning assembly.
Use the slide stop bits in the command block to stop axis motion in
non-emergencies. The slide stop decelerates before stopping and is
less abrupt than the hardware stop.
Jog Forward Input
Before the module responds to the jog forward input, the control loop must be
in manual mode.
If you apply high input (more than 10 VDC) to the jog forward input, the axis
moves in the forward direction (the direction of positive movement relative to
the zero-position offset). It continues to move until the jog forward input is low
or until the axis reaches the software travel limit, whichever occurs first.
Chapter 8 explains how to define the zero-position offset in the parameter
block.
To set up the jog forward input:
1. Connect a normally open push-button switch between the JOG FWD input
terminal (19/20) and the discrete input power supply’s positive terminal
(27).
2. Mount the jog forward switch so an operator can see the axis motion.
Leave the jog forward input terminal disconnected if you’re not using it.