Keithley 501 900 01B free download

File name 501_900_01B.pdf

STEP1 and STEP2 Stepper Motor Control Modules Control of a stepper motor requires both STEP1 and STEP2 modules. This documenta- tion treats the STEP1 and STEP2 modules as a unit. The STEP1 and STEP2 modules (see Figures 1 and 2) enable the IBM PC version of the Series 5001Soft500 package to independently control up to eight stepper motors. The STEP modules can set motor speed and direction and perform absolute and relative positioning of the motor shaft. A single STEP1 communicates with up to four STElYs, each of which connects to a single external stepper motor drive. The motor drive translates the STEP2's control signals into the proper phase codes and wattage for the selected motor. The STEP2 module is compatible with a wide variety of motor drives requiring TTL level pulse and direction control signals. The STEP2 provides low-true and high-true outputs for pulse (STEP and STEP) and direction control (CWKCW and CWKCW). A complete motor control system can be assembled using a STEP1 and STEP2, a TTL compatible motor drive, and a stepper motor compatible with the drive. A single Series 500 can control a total of eight stepper motors if stepper control is the only function. For such applications, the system does not require analog input or A/D converter modules. It can, therefore, hold two STEP1 modules and eight STEP2 modules. The STEP1 module contains a separate command buffer for each STEP2. A computer can issue several commands to a stepper motor almost instantaneously. However, the commands themselves may take seconds or minutes to be completed. Each command buffer receives all the pending commands for its associated motor, and passes the com- mands to the motor sequentially. The STEP1 module contains a status register for each of its corresponding STEP2 modules. These registers enable a program to read the status of each motor. Status flags include "motor ready for command", direction, positioning mode, limit status, "motion complete", and motor ID. Each STEP2 has a TTLlevel LIMIT input which, when taken to logic low, halts the cor- responding motor immediately. Execution of the limit condition is totally controlled by the STEP2 hardware. Triggering the limit input updates the limit flag in the status register and disables the motor. The motor will remain disabled until the control pro- gram resets the status register limit flag to "NO LIMIT". The STEP module instruction sets include commands for this purpose. The LIMIT input responds to a switch closure to ground, or to a low-going edge from a TTLlevel signal. The STEP2 also enters a limi