Servo Drives Selection Guide
Servo drives are split by command interface into pulse, analog, Modbus RTU and EtherCAT input types; the PLC output must match the input.
This guide covers the points to look at when choosing products in the Servo Drives category.
Servo drive types by command interface
The main difference between drives is where and how they receive the motion command.
- Pulse (pulse train) input: positioning is done with a pulse train coming from the PLC's high-speed pulse output; a pulse and direction signal is mostly used. PTI in Schneider Electric product names refers to this input. The product data of GMT models gives the voltage level and maximum frequency of the pulse input; your PLC output must match these values.
- Analog input: the speed or torque reference is given by an analog voltage signal; the product data states −10…+10 V input for GMT models and 0-10 V input for Isıso models.
- Modbus RTU (RS485): parameters and commands are read and written over serial communication.
- EtherCAT: an Ethernet-based real-time fieldbus standardized in IEC 61158. It is used with EtherCAT motion controllers for multi-axis synchronized motion.
- CANopen: uses the CiA 402 device profile for drives and motion control; the same profile can also be carried over EtherCAT. For the controller side, see CANopen motion controllers.
- Sercos: found on the Sercos-interface models of the Schneider Electric Lexium 32 series.
The drive's network and the controller's network must be the same; different networks cannot be connected to each other directly.
What to look at when choosing a servo drive
- Motor matching: the drive must be matched with the compatible motor series of the same manufacturer and with the motor's power. The "compatible encoder resolution" (17-bit, 20-bit, 23-bit absolute) in the GMT product data must be the same as the motor's encoder. When choosing from the Servo Motors category, compare the series of the two products; for a matched package, see the Servo Kits category.
- Mains supply: there are models with single-phase 220 V, three-phase 220 V and three-phase 400 V inputs; the drive's input must be the same as your mains supply. Delta ASDA-A2 product names do not state the input voltage; verify the voltage and number of phases from the manufacturer's data before ordering.
- Inputs and outputs: the GMT product data states the number of digital inputs and outputs and the number of analog inputs and, on some models, whether the inputs can be selected as PNP or NPN; count the signals needed for limit switches, reference sensors and brake control.
- Braking energy: there are models for which the product data states a built-in braking resistor; if there are frequent stops, a high-inertia load or a vertical axis, calculate the need for an external resistor according to the manufacturer's data.
How to read the codes in the product name
- Delta: in product names, a trailing -E indicates the EtherCAT interface and -M the CANopen interface; in the ASDA-E3 series, -L indicates the Modbus, pulse and analog input model; the power and interface are also written in the name (ASD-A2-0721-M: 750 W, CANopen).
- GMT: in the SD7 series, models with the EC code have EtherCAT, and models with the RS code have pulse, analog and RS485 inputs. In the SD7RS and SD7EC codes the trailing digits give the power (SD7RS07: 750 W, SD7EC30H: 3000 W); for models with SD1EC-SD5EC codes the power is written in the product name.
- Schneider Electric: Lexium 32 names contain the type (Compact, Advanced, Modular, Sercos) and a current value; M2 at the end of the code indicates a single-phase 220 V input model and N4 a three-phase 400 V input model. Verify the input voltage, and whether the current in the name is continuous or a peak value, from the manufacturer's datasheet. Lexium16 and Lexium18 names state the interface (PTI or PTI/Ana/MB), the power and the mains supply (1~220, 3~220).
Brands in this category
- Schneider Electric: Lexium 16, Lexium 18 and Lexium 32 series drives.
- Delta Electronics: the EtherCAT and CANopen models of the ASDA-A2 series, and the EtherCAT and Modbus/pulse/analog models of the ASDA-E3 series.
- GMT: the EtherCAT and pulse/analog/RS485 input models of the SD7 series; also drives with SD6 and GSS3 codes.
Isıso is listed with AS100A series drives with Modbus RS485 communication.
Order notes
- Products are sold by the piece.
- Schneider Electric Lexium, Delta ASDA-A2 and Isıso drives are listed as made-to-order; for these products the lead time is confirmed before the order.
- The category also contains a connector kit that is not a drive (Schneider Electric VW3M4B01); check the product name.
- Ready-made power and encoder cables between the drive and the motor are in the Servo Motor Cables category.
- You can reach a product directly by typing the manufacturer code (such as LXM32CD18N4, ASD-A2-0721-M, SD7EC30H) into the search.
Comparison and selection table
| Selection Criterion | Pulse / Analog Command Servo Drive | Fieldbus (EtherCAT / CANopen / Profinet) Servo | Low-Inertia vs Medium/High-Inertia Servo Motor Set |
|---|---|---|---|
| Control Interface | Position (Pulse+Dir), Speed (±10 V) & Torque modes | Real-time multi-axis interpolation over industrial bus | Matched flange size (60, 80, 110, 130 mm), torque (Nm) & rpm |
| Encoder Feedback | 17-bit / 20-bit / 23-bit high-resolution incremental/absolute | Multi-turn absolute encoder (retains home position) | With 24 V DC holding brake (for vertical Z-axes) or non-brake |
| Power Rating | 100 W – 3 kW (220 V single/three-phase) | 400 W – 15+ kW (220 V or 400 V three-phase) | Drive, motor, encoder cable & power/brake cable matched as a kit |
| Typical Application | Cut-to-length, labeling, indexing & 1–2 axis automation | Robotics, flying shear, electronic cam & multi-axis CNC | Low inertia: rapid accel/decel; Medium/High: heavy load matching |
Frequently asked questions
What is the difference between an EtherCAT servo drive and a pulse-input drive?
A pulse-input drive receives the position command from the PLC's high-speed pulse output as a pulse and direction signal; each axis needs its own pulse output and wiring. An EtherCAT drive receives the command over an Ethernet-based real-time network and is used with a motion controller for multi-axis synchronized motion. Your controller's interface decides the choice; verify from the product data which command inputs the drive supports.
Does a servo drive work with a servo motor from a different brand?
Most servo motors work with a drive made for their own brand or model. The drive must be able to read the motor's encoder and recognize the motor parameters; cables and connectors are also series-specific. The product data of the GMT products in this category states the encoder resolution the drive is compatible with. Use the drive with the matching motor series of the same manufacturer; if you are considering a different pairing, verify compatibility from the manufacturer's data.
When are position, speed and torque modes used?
In position mode the drive follows the commanded position; positioning and axis movements are done in this mode. In speed mode the drive follows the speed reference; it is used in systems where the position loop is closed in the controller and in constant-speed drives. In torque mode the motor torque is set according to the command; it is preferred for jobs such as winding, tension control and pressing. The GMT and Isıso product data states that all three modes are supported.
Does a servo drive need a braking resistor?
When the motor decelerates or when the load turns the motor, the motor acts like a generator and returns energy to the drive's DC bus; when the bus voltage exceeds a certain level, this energy is converted to heat in the braking resistor. There are models for which the product data states that a built-in braking resistor is present. If there are frequent stops, a high-inertia load or a vertical axis, whether an external resistor is required and its value are determined by the calculation method in the manufacturer's data.
Can a servo drive be used on a single-phase 220 V mains supply?
Yes, the category has drives with a single-phase 220 V input; in the product name this appears as "1 Faz 220VAC" or "1~220", and in the Lexium 32 series, models whose code ends in M2 have a single-phase 220 V input. Higher-power models require three-phase 400 V. Models that have "3~220" or "3 faz 220 V AC" in their name have a three-phase 220 V input and cannot be connected directly to a 400 V mains supply. Verify the input voltage from the manufacturer's data before ordering.