# AutomationDirect DURApulse GS21-21P0

Hardware · `GS21-21P0` · verification: source checked

The GS21-21P0 is a DURApulse GS20 series general-purpose AC variable frequency drive sold by AutomationDirect in an enclosed B2 frame. It takes single-phase 230 VAC input and drives a three-phase induction or permanent magnet AC motor rated 1 hp, using SVC, V/Hz, FOC or torque control modes. It has integrated dynamic braking, an RS-485 port with Modbus slave protocols, discrete and analog I/O, and a keypad mounted on the drive.

## Specification

| Property | Value |
|---|---|
| Category | vfd |
| Weight | 1.2927 kg |
| Supply voltage | 230 VAC |
| Rated power | 0.7457 kW |
| Rated current | 4.8 A |
| Frame size | B2 |
| Output type | PWM output |
| IP rating | IP20 |
| Operating temp min | -20 °C |
| Operating temp max | 50 °C |

## Connected

- Manufacturer: [AutomationDirect](https://machineschema.com/manufacturer/automationdirect.md)
- Protocols: [MODBUS ASCII](https://machineschema.com/protocol/modbus-ascii.md), [MODBUS RTU](https://machineschema.com/protocol/modbus-rtu.md)

## Safety

- Safe Torque Off (STO) is built in.
- Enclosure rating is IP20, so the drive is not protected against water or dust ingress.
- Rated ambient temperature range is -20 to +50 deg C.
- A user-supplied external fuse is required.
- Agency approvals: UL Listed file E198015; CE declaration; RoHS compliant; no UL Recognized, UL Hazardous or CSA file listed.

## Study notes

- Control modes are SVC, V/Hz, FOC and torque; output frequency range is 0.1-599 Hz and carrier frequency range is 2-15 kHz.
- Discrete I/O: 7 inputs at 24 VDC (sinking/sourcing) and 3 outputs rated 240 VAC / 48 VDC, including one Form C (SPDT) relay; relay load 3 A per point, discrete 50 mA per point.
- Analog I/O: 2 inputs (0-20 mA, 4-20 mA, +/-10 VDC, 10-bit and 12-bit resolution) and 1 output (0-20 mA, 4-20 mA, 0-10 VDC, 10-bit).
- Communications: one RS-485 port on RJ45 and one USB B port, up to 115.2k baud, Modbus RTU Slave and Modbus ASCII Slave.
- EtherNet/IP and Modbus TCP are only available through an optional communication card, not built in.
- Programming language stated as ladder; GSLOGIC drive PLC software and GSOFT2 configuration software are listed for the drive.
- Connector type is spring clamp terminals; mounting is panel or wall; drive has no integrated EMI filter and is not internally bypassed.
- Rated 4.8 A continuous and 5 A for variable torque duty with single-phase 230 VAC input; the 1 hp figure applies to 1-phase input.
- Item shipping weight is stated as 2.85 lb (about 1.29 kg), not the net drive weight.
- Supplied with a keypad (GS20A-KPD) attached to the drive and a quick start insert.

## Sources

1. [DURApulse AC General Purpose Drive: 230 VAC, 1hp with 1-phase input, (VFD) (PN# GS21-21P0) | AutomationDirect](https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/general_purpose_vfds/gs21-21p0) (accessed 2026-10-26)
2. [GS21 21P0 cutsheet](https://cdn.automationdirect.com/static/specs/cutsheet/GS21-21P0_cutsheet.pdf) (accessed 2026-10-26)

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