User guide

194 6000 Series Programmer's Guide
Implementing Ratio Following
This section covers the basic elements of implementing Ratio Following:
• Applying Following setup parameters
• Move profiles
• Performing phase shifts (FSHFC and FSHFD)
• Application scenarios:
- Electronic gearbox
- Trackball
Ratio Following Setup Parameters
Prior to executing a Following move, there are several setup parameters that must be
specified. These parameters may be established:
☞
Programming
examples — see
application examples
later in this chapter.
• Define the master and slave axes (FOLMAS)
• Define master & slave scaling factors (SCLMAS, SCLA, SCLD, and SCLV) – if required
• Define the slave-to-master Following ratio (FOLRN and FOLRD)
• Define the master distance (FOLMD) – define scaling first
• Enable the Following Mode (FOLEN)
Following
Status
(see TFSF, TFS and FS
commands)
Following Status bits 5-8 (see table below) are meant to indicate the status required for
Following motion (i.e., a master must be assigned, Following must be enabled, the master
must be moving, and for many features, the master direction must be positive).
Bits 7-8 represent master motion and master direction respectively. Unless the master is a
commanded position of another axis, it is likely that minor vibration of the master will cause
these bits to toggle on and off, even if the master is nominally “at rest”. These bits are meant
primarily as a quick diagnosis for the absence of master motion, or master motion in the wrong
direction. Many features require positive master counting to work properly.
Bit # Function (yes = 1; no = Ø)
5 FOLMAS Active.................. A master is specified with the FOLMAS command.
6 FOLEN Active..................... Following has been enabled with the FOLEN command.
7 Master is Moving............... The specified master is currently in motion.
8 Master Dir Neg.................. The current master direction is negative. (bit must be cleared to allow
Following move in preset mode–MCØ).
Define the
Master and
Slave Axes
(FOLMAS)
The FOLMAS command defines the masters and the slaves. The command syntax is
FOLMAS<±ii>,<±ii>,<±ii>,<±ii>, where each <±ii> represents the configuration
for axes 1 through 4, from left to right. (Note that the number of axes available differs by
product). The configuration for each axis (±ii) is further defined as follows:
• Sign bit (±): Specifies the count direction of the master source which will result in
positive master travel counts. The sign bit is not meant to be used simply to change the
direction of slave motion. That function can be done with the sign of the D command.
Rather, the sign bit is used to allow forward motion of the physical master (e.g., conveyor
belt, rotating wheel, or the continuous feed of material or product) to result in positive
counts. Several features described later in this document require increasing master counts
for proper operation. These include Following motion in preset positioning mode (MCØ) ,
master cycle counting, and executing GOWHEN based on master cycle position.
• First i: Selects the master input axis number (1 through 4) that you are assigning to
the slave.
• Second i: Selects the master input (input device or commanded position) according to
the axis number specified with the first i. The availability of master input sources
differs by product, as indicated in the table below.