Acceleration units:The acceleration value is calculated as:Acceleration value = x acceleration factorvelocity valuesAcceleration value means all objects containing values inuser-defined acceleration units. The acceleration unit is alsoused for deceleration.2.3.3 Positions and OffsetsInside the servo drive, there are several logical positions.Illustration 2.2 shows the relationships between them.Internal Encoder Position(-)TRC_ROTOR_POS_RAW[increments]Physical (Absolute) Position(-)TRC_ROTOR_POS[increments]Drive Position(0x2022)[user-defined position unit]TRC_POS_ACT_REAL[revolutions]Position Actual Value(0x6064)TRC_POS_ACT_ABS[user-defined position unit]Logical CAM Position(0x2020)TRC_CAM_POS[revolutions]Only up to date if CAMmode is active;otherwise, the last valueremainsPosition Actual InternalValue(0x6063)[increments]Encoder offset(set during callibration)Position offset(set during homing)FactorgroupFactor group +Position range limit(0x6078)CAM offsets130BF158.10Illustration 2.2 Servo Drive Logical PositionsThe object index is given in round brackets. The positionswithout index numbers are not available in the objectdictionary but are used internally in the firmware of theservo drive. The units are given in square brackets.The Position offset is the offset that is calculated during ahoming procedure (see chapter 2.4.4 Homing Mode). Forapplications where the zero position only needs to be setonce during the lifetime of the servo drive, this offset canbe saved to non-volatile memory (seechapter 7.7.8 Parameters 51-02, 52-04, and 52-49: ApplicationSettings (0x2016)).2.3.4 Position Limits2.3.4.1 Hardware Limit SwitchOne method to limit the positions of the servo drive is touse limit switches (left/negative or right/positive), whichare also referred to as hardware limit switches. The limitswitches must be configured using object 0x200F (seechapter 7.21.3 Parameter: Dual Analog User Inputs Configu-ration (0x200F)). When the servo drive reaches the Left(Right) Limit switch, it ramps down to standstill using thevalue set in object 0x6085 (see chapter 7.5.9 Parameter50-13: Quick Stop Deceleration (0x6085)). It is possible tocommand the servo drive out of the limit switch in theopposite direction. The states of the limit switches areindicated in object 0x2006 (see chapter 7.22.12 Parameter50-08: Motion and Input Status (0x2006)).The servo drive remains in state Operation enabled. If amotion command is issued that would direct the servodrive further in the wrong direction, the command isrejected by setting the command error bit in theStatusword. The monitoring of the limit switch is edge-triggered because the signal does not need to remain highfor the duration of the servo drive ramp-down time.The hardware limit switch is monitored in all modes ofoperation.PositionHardwarelimit switchVelocityQuick-stopdeceleration130BF159.10Illustration 2.3 Hardware Limit Switch2.3.4.2 Software Position LimitThe valid positions of the servo drive can also be limitedusing software position limits (object 0x607D: Softwareposition limit). This object indicates the configuredmaximum and minimum software position limits and isused to monitor the position limits in all available modesof operation.Supervision of software position limits requires a definedhome position (the Is homed bit in the Statusword must beset).The behavior of the servo drive in a position-controlledmode of operation differs to other modes. In a position-controlled mode of operation, the drive does not pass overthe software position limit. The target position is limited toServo Drive Operation VLT® Integrated Servo Drive ISD® 510 System22 Danfoss A/S © 01/2017 All rights reserved. MG36D10222
