The Emerson PACSystems PACMotion multi-axis motion controller (PMM345) is a high-performance, easy-to-use servo motion control module that is closely integrated with the PACSystems RX3i CPU's logic-solving and communications functions. Each PMM345 module can control up to four servo axes. An additional virtual (time-based) axis and an additional external encoder can be configured. Eight modules can be included in a single rack for a total of 40 axes.
The built-in faceplate I/O on the PMM345 has four general-purpose 24-volt digital inputs, two high-speed 24-volt digital inputs with open wire fault detection, and two general-purpose 24-volt configurable inputs/outputs. In addition to simple I/O, faceplate I/O is configurable for motion-specific functionality such as touch probe inputs, overtravel limit switches, home switches, and A Quad B encoder and marker inputs (Axis 5 only). The PMM345 also supports an optional fiber I/O terminal block (FTB).
The PMM345 provides synchronized or delayed start of up to eight axes. For electronic cam or gear applications, any number of real (motor) or virtual (time-based) axes in a rack can be used as masters for one or more slave axes on any module in a rack. For electronic cams, master and slave axes can be rescaled dynamically. A cam slave axis can be phase shifted dynamically. Two electronic gearing modes are provided, including a simple velocity synchronization and a velocity/position synchronization. Velocity-synchronized gear slaves can have moves superimposed dynamically allowing jerk-limited position adjustments. For both gearing and camming, the PMM345 uses a ramping function to synchronize a slave to a moving master.
Electronic cams can be created using the built-in cam editor in the PACSystems software or imported via CSV file. The cam editor allows master/slave points to be added in either a table or through graphical manipulation. Point data can be fitted using 1st, 2nd, 3rd, or 5th degree spline curve fitting. A cam profile can be subdivided into segments with a different curve fit degree for each segment. Up to 2048 cam profiles can be downloaded and stored on the RX3i CPU at one time. Up to 256 profiles can be selected and stored on each module. Cam profiles can be replaced dynamically as required.
Up to three interrupts are provided for each PACMotion module. One interrupt can be configured as time-based with configurable update time down to 2ms. Any of the three interrupts can be configured as I/O input event-driven interrupts.
The digital cam switch (programmable limit switch) capability of the PMM345 provides up to four outputs (tracks) using either regular or high-speed outputs on the faceplate or the FTB. Each track can have up to eight switches.
To assist with commissioning and debug, the PAC Machine Edition software provides the capability to program one diagnostic logic block that can be downloaded to the RX3i CPU and executed without altering the main program logic. The PMM345 provides the capability to log data during runtime. Using PAC Machine Edition, this data can subsequently be uploaded and displayed. The PMM345 module is designed to be compliant with the PLCopen specification for motion. All motion functionality is controlled by specialized functions and function blocks integrated into the CPU logic. Capabilities of motion function blocks include blending and buffering of blocks, and velocity, acceleration and jerk limited motion.
