The Allen-Bradley 1771-DB is a PLC 5 Basic Module. It provides an easy interface between a PLC-5 processor, 1771 backplane, and RS-232, RS-422, or RS-485 devices. It can also communicate with a remote SLC processor or remote device across a DH-485 network via a DH-485 port. It provides fast communication independent of the processors. The 1771-DB allows for data analysis and manipulation gathered from the processors and unattended report generation. It saves processor memory by solving complex math or application-specific problems. The 1771-DB has applications in various remote communication devices such as computers, printers, modems, and other third-party devices.

The 1771-DB module has an isolation voltage of 500V DC from port-to-port and port-to-backplane. It has a 32 KB battery-backed RAM and 24 KB available user memory. It has a communication rate ranging from 300 – 19.2 Kbps. It has a backplane current load of 0.75A with a DH-485 interface connected to a DH-485 port and one of 0.65A without a device connected to the DH-485 port. The 1771-DB has a time-of-day clock with a 10ms resolution and a maximum power dissipation of 4W. For installation, it takes one slot in the I/O chassis and supports BASIC and C programming languages. It requires 2 ports for RS-232, RS-422, or RS-485 connections and 1 port for DH-485 connections.

The 1771-DB module supports BASIC statements and commands and its additional 128 calls. It has a Block-transfer capability which allows complete data transfer between the processor’s data table and the module’s memory, thus minimizing user programming. The 1771-DB has 8 defined and 2 user-defined indicators for troubleshooting and indicators.