Being a multi-function fiber modem that supports asynchronic RS232, RS422 and RS485 communication modes the UT-277 is a great choice for general industrial applications. Connections from remote terminal units to hosts or Supervisionary Control and Data Acquisition (SCADA) equipment are easily made. It supports two-line half duplex RS485 and four-line full-duplex RS422.
Fiber lines are inherently resistant to EMI/RFI and transient surges, so they are ideal for data communications near heavy electrical equipment and other electrical or radio interference. The communication distance can be up to 2.5 miles (4km) for multi-mode and 31 miles (50km) for single-mode, with transmission rates of 115.3Kbps for RS232 and 460Kbps for RS422/485.
Multimode fiber cable of almost all sizes can be used, including 50/125um, 100-140um and 200um. In a point-to-point configuration, two fibers are required between the two modems, one for data in each direction.
Standards can be mixed and matched so RS-232 devices can be connected to RS-422/485 devices, replacing a converter and isolator. When working with RS-485 signals, an Automatic Send Data control signal eliminates the need for driver software and zero delay converting time is achieved. Serial side connections are on terminal blocks for RS422/485 and DB9 connector for RS232; multimode fiber side has two ST connectors.
Required external power supply is included.
Overall features
- Supports Point-to-Point Working Mode.
- Comptible with standard RS232/422/485 protocols/interfaces.
- Transmission Rate up to 115.200BPS.
- Supports 2 Wires Half Duplex and 4 Wires Full Duplex Modes.
- Transmission distance: 2.5 miles multimode, 31 miles singlemode.
- Wave length: 850nm multimode, 1310nm singlemode.
- Working environment: -40?F (-40?C) - 176?F (80?C).
- Mechanical dimensions: 95mm x 33mm x 17mm.
- External power supply included.
Electric interface:
- RS232: standard DB9 female connector with 15KV antistatic and ESD protection, max rate 120Kbps.
- RS422/485: 4-pin terminal. Automatic transmission rate detection. 15KV antistatic and EDS protection.
- Fiber interface: ST fiber optic port.
RS232C connector definition
| DB9 female | RS232C signal |
| 1 | GND |
| 2 | TXD |
| 3 | RXD |
| 4 | DTR |
| 5 | Signal GND |
| 6 | DSR |
| 7 | RTS |
| 8 | CTS |
| 9 | RI |
RS422/485 connector definition
| Terminal | Signal | RS422 | RS485 |
| 1 | TX+ | Send (A+) | A+ |
| 2 | TX- | Send (B-) | B- |
| 3 | RX+ | Receive (A+) | n/a |
| 4 | RX- | Receive (B-) | n/a |