FRM220-Serial RS-485 / 232 over Fibre Modem

FRM220-Serial RS-485 / 232 over Fibre Modem

The FRM220-SERIAL is a fibre optic modem for asynchronous RS232, RS485 and RS422 applications. The modem is available with multi or singlemode optics and can be fitted with a variety of fibre optic connectors ST, SC, FC/PC or a modular SFP option. The FRM220-SERIAL secures data transmission over EMI resistant fibre at speeds up to 256Kbps for RS232 or up to 1024Kbps for RS485/422. Both 2 and 4 wire (full and half duplex) RS485/RS422 operation is supported. The serial interface is presented as a 6 wire screw terminal block. When the FRM220-SERIAL card is placed alongside an NMC management card, remote configuration and monitoring via web browser or SNMP can be achieved on both the local and remote units.

FRM220-Serial schematic


  • Extend asynchronous serial transmission from 2km to 120km over fibre
  • In-band network management via terminal, web or SNMP (via NMC management card)
  • Supported interfaces -  RS232, RS485, RS422
  • 2 or 4 wire operation
  • full and half duplex transmission support
  • RS232 speeds up to 256Kbps
  • RS485/ 422 speeds up to 1024Kbps


Optical Interface:

  • Connector: 1x9 (SC, ST, FC)
  • Data rate: 36.864Mbps
  • Line Coding: Scrambled NRZ
  • Bit Error Rate: Less than 10-10
  • Fibre: MM 62.2/125μm, 50/125μm. SM 9/125μm
  • Distance: MM 2km, SM 15/30/50/80/120km; WDM 20/40/60/80km
  • Wavelength: MM 1310nm, SM 1310, 1550nm, WDM 1310Tx/1550Rx(type A); 1550Tx/1310Rx(type B)

Electrical Interface:

  • Connector: 6 pins Terminal block
  • Data Signal: RS485 2-wire
  • Formats: RS422 4-wire; RS232 RTS/CTS 5-wire; RS232 3-wire
  • Baud Rate: RS422, RS485 up to 1024kbps, RS232 up to 256kbps
  • Bit Error Rate: Less than 10-10

Standard: EIA/TIA RS485, RS422, RS232
Indications: LED (Power, FX Link, DI, DO, Test)
Power Input: Card : 12VDC, Standalone : AC, DC options
Power Consumption: < 5W
Dimension: 155 x 88 x 23mm (D x W x H)
Weight: 120g
Temperature: 0 ~ 50°C (Operating), -10 ~ 70°C (Storage)
Humidity: 10 ~ 90% non-condensing
Certification: CE, FCC, LVD, RoHS
MTBF: 65,000 hrs (25°C)