PMAC Quick Reference Guide The set of Q-Variables working within a command depends on the type of command. When accessing a Q-Variable from an on-line (immediate) command from the host, it is the Q-variable for the currently host-addressed coordinate system (with the &n command). When accessing a Q-Variable from a motion program statement, it is the Q-Variable belonging to the coordinate system running the program. If a different coordinate system runs the same motion program, it will use different Q-variables. When accessing a Q-Variable from a PLC program statement, it is the Q-Variable for the coordinate system that has been addressed by that PLC program with the ADDRESS command.
Each PLC program can address a particular coordinate system independent of other PLC programs and independent of the host addressing. If no ADDRESS command is used in the PLC program, the program uses the Q- Variables for Coordinate System 1. M-Variables To permit easy access to PMAC’s memory and I/O space, M-Variables are provided. Generally, a definition must be made only once with an on-line command. On PMACs with battery backup, the definition is held automatically. On PMACs with flash backup, the SAVE command must be used to retain the definition through a power-down or reset.
The user defines an M-variable by assigning it to a location and defining the size and format of the value in this location. An M-variable can be a bit, a nibble (4 bits), a byte (8 bits), 1-1/2 bytes (12 bits), a double-byte (16 bits), 2-1/2 bytes (20 bits), a 24-bit word, a 48-bit fixed-point double word, a 48-bit floating-point double word, or special formats for dual- ported RAM and for the thumbwheel multiplexer port. There are 1,024 M-Variables (M0 to M1023), and as with other variable types, the number of the M- variable may be specified with either a constant or an expression: M576 or M(P1+20) when read from; the number must be specified by a constant when written to.
The definition of an M-Variable is done using the defines arrow ( -> ) composed of the minus sign and greater than symbols. An M-Variable may take one of the following types, as specified by the address prefix in the definition: X: 1 to 24 bits fixed-point in X-memory Y: 1 to 24 bits fixed-point in Y-memory D: 48 bits fixed-point across both X- and Y-memory L: 48 bits floating-point across both X- and Y-memory DP: 32 bits fixed-point (low 16 bits of X and Y) (for use in dual-ported RAM) F: 32 bits floating-point (low 16 bits of X and Y) (for use in dual-ported RAM) TWD: Multiplexed BCD decoding from Thumbwheel port TWB: Multiplexed binary decoding from Thumbwheel port TWS:
Multiplexed serial I/O decoding from Thumbwheel port TWR: Multiplexed serial resolver decoding from Thumbwheel port *: No address definition; uses part of the definition word as general- purpose variable If an X or Y type of M-Variable is defined, the starting bit to use, the number of bits, and the format (decoding method) must be defined also. Typical M-Variable definition statements are: M1->Y:$FFC2,8,1 M102->Y:49155,8,16,S M103->X:$C003,0,24,S M161->D:$002B M191->L:$0822 M50->DP:$D201 M51->F:$D7FF M100->TWD:4,0.8.3,U 34 Programming PMAC