Laureate™ DPMs and counters offer RS-232 or RS-485 communication boards to interface with computers, PLCs or other digital devices, including the Laureate 6-digit remote display. Both boards are connected via phone jacks using standard 4- or 6-conductor phone cables. With either board, Laurel Electronics provides Windows-compatible software which allows device setup via a computer monitor.

With DPMs and counters, the information transmitted via RS-232 or RS-485 includes the latest signal value (filtered or unfiltered), peak signal value, alarm values and status. By using a serial interface board, a Laureate counter can be used as a remote display to an external device or to another Laureate.

Point-to-Point Communications with RS-232

The RS-232 option allows a Laureate meter or counter to be programmed by a computer, to output data to a computer, or to drive a panel-mount printer, remote display, or other digital device with an RS-232 interface. There can normally only be one meter or counter per RS-232 line. However, multiple remote displays can be connected to a single RS-232 line in multidrop fashion.

The RS-232 request-to-send line (RTS) can be set to a latched mode, where a single reading is transmitted when the line is taken high. This mode allows a single data transfer to be commanded by a device other than a computer.

Multidrop communications with RS-485

The RS-485 version allows multiple Laureate meters, counters and remote displays, as well as non-Laureate devices, to be connected to the same RS-485 line in parallel, multidrop fashion. Each device has its own, unique digital address. It provides for up to 31 digital addresses, so that multiple Laureates can be addressed and transmit on the same data line.

Data rates are selectable from 300 to 19,200 bps. In case of long line lengths, the RS-485 board at the end of the line can be terminated by a jumper-selectable 120 ohm resistor to minimize signal reflections. A full duplex mode with separate wire pairs for transmit and receive is offered by the RS-485 version, as is a half duplex mode with shared transmit and receive wires.

The use of RS-485 lines maximizes utilization of computer ports and simplifies plant wiring. As opposed to RS-232, RS-485 uses two pairs of balanced lines, which allow long cable runs in electrically-noisy environments. Transmission distance up to one mile are possible