The FRM220-SERIAL-SC20B provides a fiber converter solution to extend RS-232 or RS-485/422 transmission distance up to 20km over a single strand of single mode 9/125um fiber. You must pair the A model using Tx:1550/Rx:1310nm with the complementary FRM220-SERIAL-SC20A model having Tx:1310nm and Rx:1550nm instead. The converter is equipped with multiple interface circuits, for connection to RS-232, RS-423, or RS-485/422 (2 or 4 wire). The FRM220-SERIAL secures data transmission over EMI resistant fiber at speeds up to 256kbps for RS-232 or up to 1024kbps for RS-422/485. When the FRM220-SERIAL is linked to the FRM220 series chassis equipped with FRM220-NMC management card , it allows network administrators/engineers to get greater functionality through advanced SNMP/Web/In-band management features. The network administrator can manage any converter module from anywhere on the network, detect any link loss and maintain each loop.The FRM220-SERIAL-SC20B provides a fiber converter solution to extend RS-232 or RS-485/422 transmission distance up to 20km over a single strand of single mode 9/125um fiber. You must pair the A model using Tx:1550/Rx:1310nm with the complementary FRM220-SERIAL-SC20A model having Tx:1310nm and Rx:1550nm instead. The converter is equipped with multiple interface circuits, for connection to RS-232, RS-423, or RS-485/422 (2 or 4 wire). The FRM220-SERIAL secures data transmission over EMI resistant fiber at speeds up to 256kbps for RS-232 or up to 1024kbps for RS-422/485. When the FRM220-SERIAL is linked to the FRM220 series chassis equipped with FRM220-NMC management card , it allows network administrators/engineers to get greater functionality through advanced SNMP/Web/In-band management features. The network administrator can manage any converter module from anywhere on the network, detect any link loss and maintain each loop.