RS232/485 Serial over Fibre Optic Modem


  • Extend async RS-232, RS-422 or RS-485  up to 2km over multimode fibre or up to 120km over single mode fibre
  • RS-232 or RS485/422 (2 or 4 wire, full or half duplex)
  • Speeds up to 256kbps for RS-232 or up to 1024kbps for RS485/422
  • In-band management
  • Selectable data interface for RS-232/ 485
  • RS485/Async. 2W (half duplex) or 4W (full duplex) up to 1Mbps
  • Standalone RS232 console management via CH01M
  • Two wire (half duplex) or four wire (full duplex) RS-485


The FRM220-Serial is a fibre modem solution to extend asynchronous RS-232,RS-422or RS-485 transmission distance up to 2km over multimode fibre or up to 120km over single mode fibre. The converter is equipped with multiple interface circuits for connection    to RS-232or RS485/422(2 or 4 wire, full or half duplex).  The FRM220-Serial secures data transmission over EMIresistant fibre at speedsup to 256kbps for RS-232or up to 1024kbps for RS485/422.  When the FRM220-Serial/485card is placed in the FRM220 rack with NMCmanagement, in-band management allows configuring and viewing the card and remote converter's status, type, version, fibre link status, data link status and alarms.  When placed in a single slot chassis and used standalone without management, the card maybe configured by DIP switches.

RS232 RS485 Serial data over fibre


Item Description
Optical Interface

Connector FRM220-Serial: Fixed SC, ST, FC
FRM220-Serial-SFP: SFP LC
Data rate 36.864Mbps
Line coding Scrambled NRZ
Bit Error Rate Less than 10-10
Fiber MM 62.2/125μm, 50/125μm. SM 9/125μm
Distance MM 2km, SM 15/30/50km
WDM 20/40km
Wavelength MM 1310nm, SM 1310, 1550nm
WDM 1310Tx/1550Rx (type A)
1550Tx/1310Rx (type B)


EIA/TIA RS-485, RS-232


Power, FX Link, DI, DO, Test

Power Input


Electrical Interface

Connector 6 pins Terminal block
Data Signal Formats RS-485 2-wire, RS-232 RTS/CTS 5-wire, RS-232 3-wire
Baud Rate RS-422, RS-485 up to 1024kbps, RS-232 up to 256kbps
Bit Error Rate Less than 10-10

Power Consumption

< 6W


Card: 155 x 20.8 x 88mm (D x W x H)




0 ~ 50°C (Operating), -10 ~ 70°C (Storage)


10 ~ 90% non-condensing




65,000 hrs

Ordering Information

Order Code Description
CT-FRM220-SERIAL-ST002 RS-232/485 fibre converter card ST, 2Km, 1310nm, 11dB
CT-FRM220-SERIAL-SC002 RS-232/485 fibre converter card SC, 2Km, 1310nm, 11dB
CT-FRM220-SERIAL-FC002 RS-232/485 fibre converter card FC, 2Km, 1310nm, 11dB
CT-FRM220-SERIAL-ST015 RS-232/485 fibre converter card ST, 15Km, 1310nm, 12dB
CT-FRM220-SERIAL-SC015 RS-232/485 fibre converter card SC, 15Km, 1310nm, 12dB
CT-FRM220-SERIAL-FC015 RS-232/485 fibre converter card FC, 15Km, 1310nm, 12dB
CT-FRM220-SERIAL-ST030 RS-232/485 fibre converter card ST, 30Km, 1310nm, 20dB
CT-FRM220-SERIAL-SC030 RS-232/485 fibre converter card SC, 30Km, 1310nm, 20dB
CT-FRM220-SERIAL-FC030 RS-232/485 fibre converter card FC, 30Km, 1310nm, 20dB
CT-FRM220-SERIAl-SFP Serial RS-485/RS-232 fibre converter, Optional SFP (Model : SFS-50xx-xx)

More Information

Chassis and mounting options for the FRM220 family.

AC and DC power options available.  See individual products for further details.

1 Slot standalone chassis for ISDN, voice or data modules, AC or DC
1 Slot chassis with DB9 console port for Ethernet, voice or serial cards
2 Slot Ethernet, ISDN and serial chassis with console port
2 Slot chassis manageable via NMC card
4 slot Ethernet, ISDN and serial chassis, 1U
8 Slot multi service rack, 1U
20 Slot multi function chassis with Ethernet, serial and ISDN, 2u
20 Slot Ethernet aggregation rack, 2u