PMAC Product Guide Examples: Jog Commands Linearly Interpolated Moves Ix22 Ix19 = Ix16 Ix17 = Ix21 - Ix20 Ix88 - Ix87 Benefits of Using S-Curve Acceleration Profiles In an electric motor the acceleration directly translates into torque and electrical current. When no S- Curve component is programmed, the acceleration, torque and current are suddenly applied to the motor all at once as soon as it starts moving. With a programmed S-curve profile, on the other hand, the acceleration is linearly introduced resulting in a smoother transition in torque and current.
However, the acceleration rate in a pure S-curve acceleration profile is two times that necessary for a pure linear acceleration profile (see equation above). This requires in some cases a longer acceleration time when using S-curve acceleration. Motor Movement I-Variables Ix20 Motor x Jog/Home Acceleration Time : This variable determines how long the acceleration portion of the jog moves will take, regardless if a S-curve components is also programmed or not (see diagram above). Ix21 Motor x Jog/Home S-Curve Time : This variable determines the portion of the acceleration ramp that will be performed in S-curve mode.
If Ix20 is set to zero, then the acceleration ramp will take 2*Ix21 and will be executed in pure S-curve mode. Ix22 Motor x Jog Speed : This variable sets the jog velocity. If the motor x is already moving, a new jog command must be issued for the Ix22 parameter to have effect. Ix23 Motor x Homing Speed & Direction : This variable is often set with the same value as Ix22. However, what is important in this case is its sign which determines in which direction PMAC will take when searching for the home sensor. Ix25 Motor x Flag Address : This variable determines how the flags related to motor x will be used.
These flags include the end-of-travel limits, the amplifier enable and fault lines and the home flag. Programming PMAC 53