Delta MMC120 - Manual (Page 108)

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This mode is intended for use with a two-valve system, one controlling the flow rate and
the other the direction. This axis controls the flow-rate valve. The directional valve must
be controlled by other means. In this mode, the axis generates a positive drive output
regardless of the direction of the move. The drive will not go negative if the motion
controller overshoots the target. This is useful for some injection and blow-molding
applications.
When the axis is stopped, you must go into open loop mode.
Warning: This bit must be set properly when the Set Parameters command is issued.
Bit 12 - Continue Mode bit
This bit affects what happens when the module loses contact with the PLC. When this bit
is set, the module will finish any move it has started, otherwise it will halt immediately
upon detecting loss of contact with the PLC. This is useful for finishing a move that must
complete to prevent machine downtime (for example, a partial shot in an injection
molding machine).
Bit 13 - Simulate bit
When this bit is set, the drive output is set to zero and the magnetostrictive transducer
inputs are ignored. Internally the TARGET POSITION is used as the ACTUAL
POSITION . This mode is used for debugging. (The transducer error bits and LEDS will
be cleared.)
NOTE: Drive output is always 0 volts while in simulate mode; no commands,
including open loop , will change this.
Bit 14 - 15 - Prescale Divisor Bits
Prescaling may be desired on systems with long strokes. The prescale bits are used along
with the SCALE parameter to convert TRANSDUCER COUNTS to ACTUAL
POSITION . The effect is to divide the SCALE by 1, 2, 4, or 8. The divide-by factor is
specified as follows:
Counts ÷ Bit 14Bit 15
1 0 0
2 0 1
4 1 0
8 1 1
The advantage of these bits is that they let you maintain a higher resolution in the SCALE
parameter. For example, a SCALE of 31027 and a divide-by of 4 gives an effective scale
of 7756.75. Without using the divide-by bits, the SCALE would have to be rounded up
to 7757, which has less resolution—with a 64” rod, the rounded value would make a
0.002” error at 64”. Note: with the stroke is always limited to 220 inches due to the 18-
bit transducer counter resolution.
Bit 16 - Integrator Limit
When this bit is cleared, the integrator limit is 20% of full drive. When the bit is set, the