VXI VT1538A user manual Stepper Motor Control Use the command

Stepper Motor Control Use the command

SOURce:FUNCtion:STEPper <preset_pos>,<mode>,<max_vel>,<min_vel >,(@<ch_list>)

to control stepper motors. The E1538 can operate 2 or 4 phase motors in full, and half step mode. Position values are sent from the algorithm to the first channel of a 2 or 4 channel "motor group". The algorithm reads the current position from the second channel of the group.

Four-phase stepper motors that require less than 100mA phase current can be directly driven by the SCP. See Figure 29 for a connection diagram that also shows the required user-supplied output protection components.

•<preset_pos> defines the position count at algorithm start-up.

•<mode> is used to select the stepping mode. the allowable values are:

Table 1. Stepping <mode> values

<mode> string	Stepping Mode	Speed	Channel
MFSFC2	Full	Full	2
MFSFC4	Full	Full	4
MFSHC2	Full	Half	2
MFSHC4	Full	Half	4
MHSFC2	Half	Full	4

•<min_vel> is specified in steps per second and is the beginning step rate at the start of the 14 or 38 step ramp-up to <max_vel>.

<max_vel> is specified in steps per second and is the maximum step rate that will be sent to the motor after ramp-up is complete.

Figure 25 shows the relationship between these parameters. A related error message: 3120, "Minimum velocity parameter must not exceed maximum velocity parameter."

Figure 25. Relationship of min_vel, and max_vel

•<ch_list> specifies the channels that will control stepper motors. A

Agilent E1538A Enhanced Frequency/Totalize/PWM SCP 37