The RS-232 Port Sharing Device (DMM-4) is a network expansion device for modem sharing or port sharing applications in polled or contention environments. The DMM-4 allows up to four devices to share a modem/DSU or computer port. Any combination of terminals and modems may be used in a network environment.
Each port of the DMM-4 may be selected as a DCE or DTE interface.
Once installed, system and network efficiency are increased through higher host processor utilization coupled with the significant decrease in idle time between host / terminal traffic sessions.
Ideal for either synchronous or asynchronous network environments, the DMM-4 is protocol transparent at data rates up to 128Kbps. The DMM-4 may be configured to provide clocking for the entire network. To prevent data transmission errors caused by clock differentials throughout the network, an 8 bit buffer is provided. In applications where the master port and the selected port provide their own clocks, data is clocked into the buffer at the receive clock rate of the active port and clocked out using the master port transmit clock.
In applications where the Clear To Send control signal is not provided by the master port, an artificial RTS/CTS is available. Additionally, several RTS/CTS delay settings are available.
The DMM-4 provides optional Anti-Streaming circuitry. Once enabled, Anti-Streaming will automatically remove a defective terminal or modem from service if the Data / Control criteria is present for the user predefined selection period.
Housed in a sturdy metal enclosure and equipped with an internal 110/220VAC switch selectable linear power supply, the DMM-4 will provide in excess of 100,000 hours of reliable service.
The DMM-4 has a three year warranty and a 24 hour turnaround on warranty repairs.
