The Liebert UPStation GXT is a range of on-line UPS units produced by Liebert Corporation, covering 700 VA to 10 000 VA in 120 V, 208 V, and 240 V variants. The rear-panel communications interface is a standard 9-pin D-SUB female socket that supports both RS-232 smart serial signalling (via pins 2 and 3) and simple open-collector/emitter status outputs for low-battery and utility-fail conditions. Remote shutdown can be triggered either by applying 5–12 V DC to pin 4 during battery operation, or by shorting pin 6 to pin 5 (common) in any mode. Power-management monitoring requires the Liebert SiteNet 1 shutdown kit, which includes a proprietary interface cable and software.
9 pin D-SUB female connector at the UPS
| Pin# | Function |
|---|---|
| 1 | Low Battery (Optocoupler Collector: +V) |
| 2 | UPS TxD |
| 3 | UPS RxD |
| 4 | Remote ShutDown (+5..12VDC, 10 mA max); on battery operation |
| 5 | Common |
| 6 | Remote ShutDown (Short to pin 5); any mode operation |
| 7 | Low Battery (Optocoupler Emitter: -V) |
| 8 | Utility/Mains Fail (Optocoupler Emitter: -V) |
| 9 | Utility/Mains Fail (Optocoupler Collector: +V) |
Notes
- The connector on the UPS rear panel is a standard DB-9 (DE-9) female socket; the mating cable plug is male.
- Maximum voltage and current on pins 1, 7, 8, and 9 (open-collector and open-emitter outputs) shall not exceed 80 V DC and 10.0 mA. A 330 Ω resistor is shown in the reference circuit diagram.
- Pins 1 and 7 form the Low Battery optocoupler pair (collector and emitter respectively); pins 8 and 9 form the Utility Fail optocoupler pair (emitter and collector respectively).
- Pin 4 remote shutdown is active only during battery operation; pin 6 remote shutdown (short to pin 5) functions in all modes of operation.
- The same pinout applies across the full GXT product family, including the 6 kVA and 10 kVA 208 V/240 V variants.
Signals
- Pin 1 — Low Battery — open-collector output (+V side of optocoupler); max 80 V DC, 10.0 mA.
- Pin 2 — UPS TxD — RS-232 transmit data from UPS to host computer (smart serial mode).
- Pin 3 — UPS RxD — RS-232 receive data from host computer to UPS (smart serial mode).
- Pin 4 — Remote Shutdown — apply 5–12 V DC (10 mA max) to initiate shutdown; active during battery operation only.
- Pin 5 — Common — signal common/return for all circuits.
- Pin 6 — Remote Shutdown — short to pin 5 to initiate shutdown; active in any mode of operation.
- Pin 7 — Low Battery — open-emitter output (−V side of optocoupler); max 80 V DC, 10.0 mA.
- Pin 8 — Utility/Mains Fail — open-emitter output (−V side of optocoupler); max 80 V DC, 10.0 mA.
- Pin 9 — Utility/Mains Fail — open-collector output (+V side of optocoupler); max 80 V DC, 10.0 mA.
References
- Liebert UPStation GXT 700–3000 VA 120V User Manual — Liebert / Vertiv (January 2000)
- Liebert UPStation GXT 700–3000 VA User Manual, page 14 — Communications Interface Port — Liebert Corporation
- Liebert UPStation GXT 6 & 10 kVA 208V & 240V User Manual, page 28 — Liebert Corporation