Overview

The Automation & Electronics SDAO was designed to provide analog output expansion capability for Programmable Logic Controllers (PLCs). With a low power requirement and a wide operating temperature range, the SDAO is ideal for use in remote 120 V_AC, 24 V_DC, or solar powered distributed I/O systems. It can also be used as a stand-alone MODBUS analog output module.

The SDAO is a microprocessor based 2 channel 4-20 mA analog output card. The outputs can be used in remote or local power mode. In remote power mode, the 4-20 mA loop power is provided externally. In local power mode, the SDAO provides the 24 V_DC loop power. Onboard jumpers configure the output types. The onboard microprocessor controls the analog outputs on this card from communicated values from host systems or master controllers via a serial data highway.

The data highway is implemented using the built in RS-485 serial port. All of the Smart Card series can be daisy chained together using these serial ports. Each Smart Card responds to MODBUS polls or commands from a master. An onboard address selector switch allows each card to be easily configured for any MODBUS address. This RS-485 data highway can then be used to create a scalable, flexible input / output expansion array.

Features