For the stepper motor drives belonging to the xS10, DS30 and DS5x series the phase current is expressed in Arms, i.e. effective current. Instead, other manufacturers characterize their products indicating the peak current (sometimes also referred to as maximum current- Imax) and
this does not allow to get the maximum torque from the motor.
The rms value of a sinusoidal current is equivalent to 1,41 times the peak current (about 40% more) therefore, for example, a drive used in microstepping and calibrated for a phase current amounting to 5Arms is equivalent to a drive by 7,05A of peak.