Delta RMC151 - Manual (Page 161)

3 Controller Features
The amount of space required for the computation buffer and curve object depends on
several factors. The most important factor is the interpolation method to be used.
Formulas for calculating the memory requirements are given below.
Constant and Linear Interpolated Curves
These two types of curves do not require a computation buffer. The curve object sizes are
given in the chart below:
RMC75E
RMC150E RMC75P
RMC75S
Curve Size 8xN + 112 bytes 8xN + 88 bytes
Cubic Interpolation Curves
The memory requirements for cubic curves depend on the options and characteristics of
the curve. The term "simple curve" below means that the curve has no fixed-velocity
points or constant-velocity segments, which can be added by the Advanced curve data
format or the Overshoot Protection and Auto-Constant Velocity interpolation options. The
term "advanced curve" below describes a curve that does have at least one fixed-velocity
point or constant-velocity segment.
The following charts show the memory requirements for simple curves:
Simple Curves with Zero- or Natural-Velocity Endpoints
RMC75E
RMC150E RMC75P
RMC75S
Curve Size 20xN + 144 bytes 20xN + 120 bytes
Computation
Buffer Size
16xN + 64 bytes 8xN + 24 bytes
Simple Cyclic Curves
RMC75E
RMC150E RMC75P
RMC75S
Curve Size 20xN + 120 bytes 20xN + 96 bytes
Computation
Buffer Size
48xN + 32 bytes 24xN + 8 bytes
The sizes for advanced curves are difficult to compute, but will generally be at least as
large as the values shown in the Simple Curves with Zero- or Natural-Velocity
Endpoints chart above. The best way to determine the size required by an advanced
curve is to add the curve and look at the size reported in the Event Log.
Memory Requirement Examples
Example 1
How much Curve Store memory is used to add a 10,000-point Simple Cubic Curve with
Zero-Velocity Endpoints to the RMC75E using the Curve Add command?
Downloading this curve using the Curve Add command will require the Partial Curve Data
Format, and therefore require a re-assembly buffer. If we use the Partial Curve –
Evenly-Spaced format (see Curve Data Formats), then the Total Curve Data Length will
be 10,004 registers. Therefore, our re-assembly buffer will require 4xTCDL + 32 or
40,048 bytes.
Next, because this curve uses the cubic interpolation method, the curve will require a
Computation Buffer. Using the charts above, we find that the Computation Buffer for a
Simple Cubic Curve with Zero-Velocity Endpoints will require 16xN+64 bytes or 160,064
bytes.
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