The digital phase-input (F) level (HI or LO) selects which pair turns on and corresponds to the direction of current flow through the winding. The current controls, (I0 and I1) select one of four comparators; zero, low, medium, or full. The output is therefore a series of current pulses equal in amplitude and separated by the period of fixed time off. The value of the current sense resistor is pre-selected to produce a current amplitude equal to that of the current rating of the motor winding. If I0 and I1 select a comparator other that FULL, then the sense resistor feed-back voltage trips at less than full current. The reference voltage of the comparators is also available as an input to the device. By externally controlling this reference input, the output current can be varied between zero and full (i.e. microstepping).
The driver card contains three sections: (1) the step generator, which controls the digital levels of the phase (F) inputs; (2) the drivers; and (3) the Auto-Park gate, which if installed, controls the output-current digital input, PRK, automatically. The step generator is a counter-PROM configured as a four-eight- sixteen step counter. The outputs of the counter are combined through PROM gates into two outputs which control the phase inputs (F) of the two driver IC's. Each step-clock causes the step counter to toggle one step and the PROM decodes a pair of phase commands to the drivers which cause a winding current direction change resulting in a one step rotation of he motor. The direction input, input directly to the counter, directs the decode to produce a CW or CCW rotation.
INSTALLATION AND OPERATION. Before operating the MS & MM series, that the input connections are correct for that mode. Refer to the installation wiring diagrams found in the back of this manual. Locations of jumpers and signals are identified on the bottom SMCe of the unit circuit board. The configuration of the MS series requires attention to four areas: step size jumper and PROM type, power supply voltage, motor winding connection, and current control dial-pot setting. Refer to driver label for maximum current and voltage limits of the particular model. Refer to the Appendix section in the rear of this manual for details.
(1) POWER SUPPLY & MOTOR CONNECTIONS
Signal Name Terminal Strip TS1 Data Connector P1
VMMTS1-1none
In general, the MS series requires an unregulated source of D.C. voltage connected to VMM. The current output must equal 1.414 the full rating of one motor winding. The voltage can be between 12 and 45 volts D.C. (maximum). The higher voltage is required only for higher step rates. In general, do not use a regulated power supply as performance is reduced. Refer to the unit label for the VMM maximum of that model.
If the optional +5vdc TTL supply is not installed, then an external 150ma digital supply is connected to the TS1-8 VCC connections. TS1-5 is provided for ground return. TS1-8 is protected by a 6.8vdc TRANSORB. The VCC is ALSO common through the digital control connector P1-13 & 14. The +5vdc can be furnished by: (1) the computer or controller power supply only, or both. If the system power is not controlled by one switch, always isolate the driver systems with a diode in the VCC connection. In any case, controller VCC and driver VCC MUST BE COMMON or other interface connections are required (opto isolation).