Omega Vehicle Security OMG-COMM2-EX manual Technical Description, Features, Line Termination

Technical Description

Technical Description

The OMG-COMM2-EXadapter utilizes the 16550 UART chip. This chip features programmable baud rate, data format, interrupt control and has a 16 byte transmit and receive FIFO.

Features

∙Full independent operation of ports allowing two ports RS-232, two ports RS-422/485 or one port of each.

∙Addressable as COM1: - COM4: or any other I/O address up to 3FF Hex.

∙‘Shareable’ IRQs allow more than one port to share a single IRQ provided the proper driver is used..

∙IRQs 2/9-5, 7, 10, 11, 12, 15 supported

∙Support for non-standard baud rates available. These baud rates (such as 31.25K or 76.8K baud) are supported by installing a different oscillator. Please consult Technical Support for more information.

Modem Control Signal Considerations

Some software packages require the use of the modem handshake signals such as CTS or DCD. Refer to your application software manual to determine the requirements for modem control signals. If no requirements are mentioned, a safe configuration is to tie DTR to DSR and DCD, and tie RTS to CTS. This configuration will typically satisfy the modem control signal requirements for most communications software.

Line Termination

Typically, each end of the RS-422/485 bus must have line terminating resistors. A

100ohm resistor is across each RS-422/485 input and a 1K ohm pull-up/pull- down combination bias the receiver inputs. If more than two RS-485 nodes are configured in a multi-drop network, only the nodes at each end of the bus should have the 100 ohm resistors installed.

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