The ONSITE-SP-MM fiber optic modem supports asynchronous RS-232/485/422 communications. It is the best choice to connect the remote terminal unit (RTU) with the HOST or SCADA controller. It supports RS-232/485/422 asynchronous protocols; it can be mixed and matched to use 2 RS-232, RS-485 or RS-422 ports, and it supports 2 wires (half-duplex) RS-485 and 4 wires (full-duplex) RS-422 mode. The RS-485 mode supports data transmission (TXD or SD) control, this enhances the adaptation to most of the software. Fiber optic MODEM supports lots of optic connections between asynchronous serial ports. It supports 2 asynchronous serial devices to communicate under full-duplex or half-duplex via optic fiber; the communication distance can be as far as 4km at multimode, and 20km at single mode. The fastest transmission rate for RS-232 can be 115.2Kbps, and RS-485/422 can be 460Kbps. Ports with different electronic standards can be mixed and matched to use; it is without problem to connect RS-232 devices with RS-485/422 devices. This is a good replacement of RS-232 to RS485/422 converter, which with EMI/RFT features.

ONSITE-SP-MM supports two signal data transmission: transmit and receive data. At the same time, it is with RS-485/422 data transmission auto control circuit; Zero delay conversion; all the serial ports is connected via terminal block.