Specifications
Appendix A 
99 
A.9 FRM220-Serial/485 In-band managed RS-485/422/232 Fiber Modem 
The FRM220-Serial/485 provides an Asynchronous Fiber Modem solution to extend RS-485 or RS-232 
transmission distance up to 2km over multimode fiber or up to 120km over single mode fiber. The modem is 
equipped with multiple interface circuits for connection to RS-232 or RS-485/422 (2 or 4 wire, full or half duplex). 
The FRM220-Serial/485 secures data transmission over EMI resistant fiber at speeds up to 460kbps for RS-232 or 
up to 1024kbps for RS-485/422. When the FRM220-Serial/485 card modem is placed in the FRM220 rack with 
SNMP management, in-band management allows viewing the card and remote modem's status, type, version, fiber 
link status, data link status and alarms. Both card and remote can be configured to enable or disable the port, reset 
the port and set the interface type. 
Features 
•  Extend asynchronous serial transmission from 2km to 120km over fiber 
•  In-band network management 
•  Manage via terminal, web or SNMP in FRM220-CH20 chassis 
•  Software selectable data interface for RS232/ 422/ 485 
•  Software selectable two wires (half duplex) or four wires (full duplex) RS485 
•  Software selectable three or five wires RS232 
•  Speeds up to 460kbps for RS232 (Async. mode) 
•  Speeds up to 1Mbps for RS485/ 422 (Async) 
Specifications 
Ports 
Optical Interface 
Connector : 1x9 (SC, ST, FC) or SFP LC 
Data rate : 36.864Mbps 
Line coding: Scrambled NRZ 
Bit Error Rate: Less than 10
-10
Cable type : MM 62.2/125μm, 50/125μm. SM 9/125μm 
Distance : MM 2km, SM 15/30/50/80/120km, WDM 20/40/60/80km 
Wavelength: 1310nm, 1550nm, 
Electrical Interface 
Connector : 6 pins Terminal block 
Data Signal Formats 
RS485 2-wire 
RS422 4-wire 
RS232 RTS/CTS 5-wire 
RS232 3-wire 
Baud Rate: 
 RS422, RS485 up to 1024kbps 
 RS232 up to 256kbps 
Standard  EIA/TIA RS485, RS422, RS232 
LEDs  Power, FX Link, DI, DO, Test 
Power DC In 12V 
Power Consumption 
< 5W 
Dimension (D x W x H) mm  155 x 88 x 23mm 
Weight 120g 
Temperature 
-10~60° C (Operating) ,-20~70° C (Storage) 
Humidity 10~95% non-condensing 
Certification  CE LVD/EMI, FCC, RoHS 
MTBF 
65,000 h (25° C) 
This product includes the following models: 
•  FRM220-Serial/485 (6 pin terminal block and fixed fiber transceiver) 
•  FRM220-Serial/485S (6 pin terminal block with SFP) 










