Emerson FM-3 - Manual (Page 144)

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FM-3 Programming Module Reference Manual
Jog.1.MinusInitiate ‘Sync,Vel=1.000in/in
Gear Stop
Gear Stop will stop gearing motion that has been initiated from a program.
Example:
Gear.Initiate
Wait for DriveInput.2=ON
Gear.Stop
Gear.Initiate
Gear Initiate will initiate gearing from a program. Gearing will remain active until the
Gear.Stop command is used.
Example:
Gear.Initiate
Wait for DriveInput.2=ON
Gear.Stop
Motion Modifiers
Using Last
When the Using Last instruction is inserted after a motion initiate instruction, the time (or
master position in synch motion) of the last command complete is used as the starting point
of the motion profile. Whenever a motion profile is complete, the time/position is
automatically captured behind the scenes. The Using Last instruction simply references this
“automatically” captured time or position.
The FM-3 module performs motion based on a concept called the timeline. The timeline
allows for accurate and repeatable motion with respect to a single point in time. The timeline
guarantees that all motion profiles occur at the right time with respect to each other.
If Index0 takes 3 seconds to complete, and Index1 takes 5 seconds to complete, by initiating
Index0 and then Index 1 in a program, the user would expect these profiles to take a total of
8 seconds to complete. It is possible though, that because of processor timing, Index.1 does
not start at exactly the same time Index0 is complete. Therefore, the two profiles could take
slightly more than 8 seconds to complete. Although the amount of time lost is extremely
small (less than 5 milliseconds), over a long period of time, this lost time can accumulate.
Keeping the timeline intact is most important in applications using synchronized motion.
This is because in synchronized motion, time is replaced by master encoder motion. If time
is lost in a synchronized motion application, then master distance is lost, and the follower
position is off with respect to the master.
Prior to A7 firmware in the FM-3 module the user had no control over the timeline. If a
motion initiate command was seen within 5 milliseconds from the last time a motion profile
was completed, the processor assumed that the user wanted to initiate the motion from the