86 Communication profilesSpeed Actual (AC/DC drive object)This attribute indicates the actual speed at which the drive isoperating. The units are scaled by the SpeedScale attribute of theAC/DC drive object. See Table 4. for details.Scalar modeWhen the drive is operating in the scalar mode, the drive providesthe adapter module with a frequency actual. The ODVA AC/DCdrive profile uses rpm units for the speed actual. The ODVA SpeedActual is calculated as follows:whereFor example, for a 4 pole 60 Hz motor (Mss = 1800 rpm) with a unitof 1 rpm and a Drive frequency actual of 30 Hz, the ODVA SpeedActual is:Osa = ODVA Speed ActualDfa = Drive frequency actual in HzUs = ODVA speed unit (see 10 ODVA SPEED SCALE on page 41)Mf = Motor nominal frequency in HzMss = Motor synchronous speed in rpm (not motor nominal speed)UsMfMssDfaOsa ××=9001rpm60Hz1800rpm30HzUsMfMssDfaOsa =××=××=
