Double D Electronics Ltd.DDA209-01 Redundant Serial Link Manager
- Dial-up override for leased line link
- Remote peripheral support for RC&M systems
- Manages comms at remote site
- Free standing modem-sized box
The DDA209-01 simplifies management of main and standby communications links for remote equipment within RC&M systems. In particular it allows modem dial-in to interrogate remote equipment either as a test, or when the permanent link has failed.
The DDA209 sits at the remote site, with one serial port connected to the local equipment. The interface supports both RS-232 and 4-wire RS-422/485, so several items of equipment may be connected to the local bus.
One host serial port is intended to be connected to a dedicated serial link, and this port supports RS-232 and 4-wire RS-422/485.
The second host serial port supports RS-232 only, and is intended to be connected to a dial-up modem.
The unit supports popular baud rates up to 115200 baud without reconfiguration.
In normal operation the first host serial port is connected through to the equipment, and communication takes place transparently.
When an incoming call is detected on the modem the permanent link is broken, and the modem is able to communicate with the equipment after a configurable delay. It is envisaged that the modem will only be used when the host detects that the permanent link has failed.
Communication reverts to the permanent link when the modem call hangs up.
Data Sheet: DDA209.PDF.
