Delta RMC151 - Manual (Page 777)

8 Command Reference
Mid-Pos The sine wave will start at the center (zero degrees) and move in the positive
direction.
See Mid-Pos and Mid-Neg Details below.
Pos Peak The sine wave will start at the positive peak (90 degrees).
Mid-Neg
The sine wave will start at the center (180 degrees) and move in the negative
direction.
See Mid-Pos and Mid-Neg Details below.
Neg Peak The sine wave will start at the negative peak (270 degrees).
For example, if the Start Location is Auto, the Offset is 3, and the Amplitude is 1, then
the Target Position must be at 2, 3, or 4 when this command is issued. If the Start
Location is Pos Peak, the Offset is 10, and the Amplitude is 2, then the Target Position
must be at 12 when this command is issued.
The diagrams below show the start of the sine wave for the Start Location options.
Mid-Pos Mid-Neg
Neg Peak Pos Peak
Mid-Pos and Mid-Neg Details
If the Start Location is Mid-Pos or Mid-Neg, in order to prevent a sudden jump in the
velocity, the frequency will be logarithmically ramped from zero Hertz to the requested
frequency during the first quarter cycle. Therefore, the first quarter cycle will not be a
true sine function, and the first quarter cycle will take longer. See the Mid-Pos and Mid-
Neg images above. If a sine move stops at the middle, the same type of ramping will
occur in the last quarter cycle.
To achieve a different ramping behavior for Mid-Pos or Mid-Neg start locations, do the
following:
• Send the Sine Start command with the frequency set to zero. The sine wave will
start, but there will be no motion.
• Use the Change Target Parameter command to ramp the frequency to the desired
value. The Change Target Parameter command provides great flexibility in defining
the ramp.
Note: For Start Locations Mid-Pos or Mid-Neg, very low frequencies, such as 0.0001 or
less, may cause an irregular Target Position. Test any very low frequencies before using
them.
Note: For Start Locations Mid-Pos or Mid-Neg with a non-zero starting frequency,
changing the frequency with the Change Target Parameter (80) command is not allowed
until the sine wave has reached the first positive or negative peak.
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