I. Introduction High-precision position control is frequently required in the machining and manufacturing industries. While DC or AC servo drives are commonly used, they are costly. This paper proposes a solution using the TD3100 frequency converter manufactured by Emerson Network Power Co., Ltd. II. Brief Introduction to TD3100 Distance Control Principle The TD3100 is an elevator-specific frequency converter developed by our company based on the high-performance vector frequency converter TD3000, and is highly favored by elevator manufacturers. Its distance control function enables self-learning of floor distances and direct high-precision stopping. Users do not need to calculate deceleration points, simplifying software design and leading to its widespread application in elevators and automated warehouses. The frequency converter learns and stores the height information of each floor in its memory through encoders. During operation, if a given floor distance is required for control, the frequency converter automatically calculates the deceleration point and stops. The target floor information is obtained from terminals F1 to F6 when the floor enable terminal FLE is active. If the distance control is based on a given REQ request signal, the inverter will automatically calculate the deceleration point for each floor. This can be output to the controller in advance via the Y1~Y4 programmable output terminals. After receiving the deceleration signal for each floor, if a stop is required, the controller will send a stop request signal REQ to the inverter, which will then decelerate and stop normally according to the deceleration curve. The timing sequence for both distance control methods is shown in Figure 1. III. Positioning Control Method with Fixed Two-Point Distance Using TD3100 For fixed two-point positioning control, equivalent to an elevator with only two floors, limit switches need to be installed at both endpoints. Distance self-learning is performed between the two points, and the distance control is directly based on the given stop request. 1. Self-learning: The self-learning connection circuit is shown in Figure 2(a). Short-circuit UPL and DWL, and connect the left and right limit switches in parallel as leveling signals to UPL and DWL. The self-learning start position should begin outside the limit switch on either the left or right end. If it cannot leave the limit switch position, self-learn first, and then adjust the leveling distance (F4.07) or floor height (F4.09) during normal operation to ensure positional accuracy. Set F4.00 to 2, and set F4.01 according to the position width for automatic frequency division coefficient calculation. During self-learning, close the FWD and SL terminals to start self-learning. Note that after the limit switch activates, remove the FWD command to complete the learning. Check the values ​​of F4.08 and F4.09 to see if they are recorded correctly. If the acceleration/deceleration time is too long or too short, it can be resolved by adjusting F3.11 to F3.16. 2. During normal operation, calculate and set F1.07 according to Equation 1, where D is the roller diameter at the control linear velocity and is the mechanical reduction ratio. Set F5.00=15, select X1 terminal as distance control enable function, and adjust the S curve according to the required operating efficiency of the process. Finally, the stopping position accuracy can be adjusted by adjusting F3.02 and F3.21. According to the wiring in Figure 2(b), control the three commands FWD, REV, and INS. During normal operation, only the FWD/REV signal needs to be controlled. INS is the jog command. When jogging, first enable INS, and then enable the FWD/REV command to control the jog left or right movement. 3. Application in the glass screen transfer machine The structure of the glass screen transfer machine is shown in Figure 3. It is driven by a 2.2kW motor with a rated voltage of 380V, a rated operating frequency of 50HZ, a rated current of 5.0A, a rated speed of 1420r/m, and a reduction ratio of 1:17. It is equipped with two proximity switches, with the distance between proximity switches #1 and #2 being approximately 1400-1800 mm. The transfer platform carries a load of approximately 150-170 kg. The transfer machine is required to move and position between two limit switches, with a positioning accuracy error within 3 mm. The single-stroke movement time is approximately 2-3 seconds, meaning the time from accelerating to constant speed from limit switch #1 to decelerating and stopping at limit switch #2 must be completed within 2-3 seconds. Following the wiring diagram in Figure 2(a), with F4.00 set to 2, first, the machine is moved to one side by closing INS and REV terminals, then the self-learning process is completed by closing FWD and SL terminals. To improve operational efficiency, the relevant parameters of the S-curve were set to their maximum values. The brake control delay times F7.00 and F7.01 were set to zero, and the starting frequency and start-up waiting time F3.00 and F3.01 were also set to zero. The S-curve parameters F3.02, F3.11, F3.12, F3.14, and F3.15 were all set to 2.400 m/s, F3.10, F3.13, and F3.21 were all set to 2.00 m/s, and F3.02 was set to 0.3 m/s. The result was stable operation, fully meeting the process accuracy requirements, and achieving the positioning effect of servo control. IV. Multi-point Distance Fixed Positioning Control Method Using TD3100 For applications such as automated warehouses and automated parking systems requiring X, Y, and Z three-dimensional multi-point positioning motion control, using TD3100 can greatly simplify the circuit, reduce costs, and improve reliability. Since the maximum number of floors can reach 128, distance control based on a given target floor is exceptionally simple to use. The system using the TD3100 automated warehouse is shown in Figure 4. In the figure, the UPL and DWL signals can use the user's leveling switch signals, or the UPL and DWL can be directly shorted to COM. FLE is the destination layer enable terminal; when it is active, the given layer signals F1 to F7 are active. INI is the current layer initialization terminal; when it is active, the current layer is restored to the given layers F1 to F7. As can be seen from the comparison in the figure, communication control simplifies the wiring, saves resources, and reduces costs. It should be noted that this function currently requires non-standard customization. Of course, the system also needs to perform layer height self-learning before application. The self-learning method is the same as described in the previous section; simply set the total number of layers F7.00 according to the actual situation. V. Positioning Control Method for Two-Point Distance Variation Using TD3100 When implementing positioning control for two-point distance variation using TD3100, the method is basically the same as the positioning control method for fixed two-point distance. The only difference is that the layer height F4.09 must be manually or automatically changed while the system is parked, and then the operation can proceed. Due to the difficulty of manual modification, communication control via a host computer is generally required. Additionally, since distance-based control is used, two limit switches are needed to determine the correct position to prevent mechanical impact during vertical or horizontal positioning. This function is typically used in multi-motor, multi-axis, high-precision distance control systems such as intelligent digital stage control. A modern stage drive system using PROFIBUS-DP fieldbus control is shown in Figure 5. This system uses PC control, with either a built-in Siemens plug-in PROFIBUS master control board CP5611 or CP5412, enabling both manual and automatic control. The adapter uses an Emerson PROFIBUS-DP adapter TDS-PA01, which directly interfaces with the TD3100. The purpose of using PROFIBUS control is to achieve high real-time control accuracy and fast response time, given the large number of stage motors, thus achieving both speed and accuracy. VI. Conclusion Besides its application in elevators, the TD3100, through flexible configuration, can be applied to various situations requiring positioning and distance control, effectively reducing hardware and software design costs and improving control system reliability.