Diamond Systems EMERALD-MM-8E/EL : EMM-8EL-XT Rugged PCI/104-Express 8-Port Serial Module with Opto-isolation

Serial links that run the length of a vehicle or between cabinets pick up ground potential differences, and a non-isolated port can pass that fault straight to the host. The EMM-8EL-XT is the eight-port isolated build in the Diamond Systems EMERALD-MM-8E/EL series, a PCI/104-Express serial I/O module that isolates every port independently to 2500 V RMS.

The module connects to the host through a PCIe x1 link on the PCIe/104 OneBank connector. A 16550-compatible octal UART with 256-byte transmit and receive FIFOs and automatic RS-485 transmit control drives all eight ports, with an SP330 multiprotocol transceiver on each, so standard serial drivers in most embedded operating systems recognise it. An on-board microcontroller holds the configuration in flash and loads it at power-up, which leaves no jumpers to set or shake loose.

Each port on the EMM-8EL-XT is set in software for RS-232, RS-422 or RS-485, with programmable 120 ohm termination, at up to 1 Mbps in RS-232 mode or 10 Mbps in RS-422/485 mode. Every port has ±15 kV ESD protection and its own latching connector. Eight auxiliary lines work as digital inputs or outputs, and seven of them can read 12-bit analogue inputs on 0 to 2.048 V or 0 to 3.3 V ranges. The EMM-4EL-XT keeps the isolation with four ports, and the EMM-8E-XT offers eight non-isolated ports for shorter runs.

Power is 5 V DC at around 160 mA typical with outputs unloaded. Staggered turn-on of the isolated power circuits limits inrush current at start-up, and unused ports can be powered down. The EMM-8EL-XT operates from -40 to 85 °C at 5 to 95% humidity, non-condensing, and Diamond Systems specifies MIL-STD-202G compatible shock and vibration. A graphical control panel, a console application and Windows and Linux drivers handle configuration and control.