Table of Contents
Advertisement
FM-4 Programming Module Reference Manual
updated via fieldbus, by simply writing to the index position parameter. If the analog input's Destination is set to an Index
number, the index's position value will be updated by the Analog to Position scaling found in the Analog Input view.
A Registration Index runs at the specified velocity until a registration sensor is seen or until it reaches the Registration Limit
Distance. If a Registration Sensor is seen, then the index runs an additional Registration Offset distance.
Rotary Plus and Rotary Minus type indexes are typically used in applications which use rotary rollover. These absolute
indexes are forced to run in a specific direction regardless of the starting point.
TimeBase
This list box selects the Time Base for the index velocity and acceleration/deceleration. Realtime and Synchronized are the
allowed selections.
Distance/Position
The Distance/Position parameter is a signed value which specifies the distance the index will travel (incremental index) or
the absolute position the index will move to (absolute index). In the case of an incremental index, this parameter also
determines the direction the index will travel. If an index type of Registration is selected, then this is a limit distance, or the
maximum distance the index will travel if a registration sensor is not seen.
Velocity
This sets the target velocity for the index profile. The velocity parameter is unsigned and must be greater than zero. Direction
of the index is not determined by the velocity, but by the Distance/Position parameter.
Acceleration
Average Acceleration rate used during the index. Units are specified on the User Units view.
Deceleration
The Deceleration parameter specifies the deceleration value to be used during the index in user units.
Timed Indexes
A Timed Index allows the user to specify the amount of time in which to perform an index rather than specifying the Velocity,
Acceleration, and Deceleration. The processor in the FM-4 will automatically calculate the necessary velocity, accel, and
decel in order to achieve the programmed distance in the specified time. A Timed Index can not be compounded into or out of.
All index types can be specified as a Timed Index, except for Registration type indexes. This is because a registration index
does not have a specified distance or absolute position. During a registration type index, the registration sensor could activate
at any time, and therefore it is impossible to calculate the necessary velocity, accel, and decel. If Registration type is selected,
then the Time check box will become disabled.
Based on the Distance entered (or Position for Absolute indexes) and the Time value specified, the calculations could result
in extremely high Velocities, Accels, and Decels. To avoid damage to mechanical parts, or potentially dangerous situations,
the user is allowed to enter the Maximum Velocity, Acceleration, and Deceleration used for the calculations. The results of
the firmware calculations will never exceed the maximum values specified.
Figure below shows a screen capture in which the Time check box has been enabled. Notice how the parameters which
normally say Velocity, Acceleration, and Deceleration have changed to say Max. Velocity, Max. Acceleration, and Max.
114
Advertisement
Table of Contents
