Compaq MTEK6000 user manual Optional Equipment, Analog Output AO Option

MTEK6000 SERIES USER'S MANUAL

CHAPTER 4: OPTIONAL EQUIPMENT

ANALOG OUTPUT (AO) OPTION

The Analog Output Module (part # 1021- 0001B-001) and connecting cable (part # 1002-0245B-001) provides a two-wire, loop-powered, optically isolated, precision 4-20mA output. This module interfaces with the MTEK6000 series product line to provide a 4-20mA output for flow rate, pressure, or numerous other control and monitoring applications. Up to two modules can be installed in the MTEK6000 in place of the batteries by using the AO module adapter plate, (Metretek stk #1008-0011B- 001).

Power for the digital interface section of the AO is selectable by using the DIPswitches, and can be supplied by Vcc of the MTEK6000 or from the main supply voltage. The AO module interfaces to an MTEK6000 series product via the standard I2C serial interface bus. The MTEK6000 unit requests the desired mA output from the AO module using this bus. An I2C digital I/O chip is used to send the information to the analog output section of the AO board.

The analog output section of the board derives its power from the current loop, and is optically isolated from the digital control interface section. The analog output section receives commands from the digital I/O chip through opto-isolators. Commands are in the form of a serial data stream. The AO module provides 4-20mA output signals with a resolution of 1 part in 65536 (16 bit). The D/A also allows for over-ranging of the output to a minimum of 3.5mA and a maximum of 24mA. The field interface to the D/A is a simple two-wire connection. Reverse polarity protection is provided.

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