Acces I/O products E-RDAG12-8, Руководство пользователя, Страница: 6 / 38

Chapter 1: Introduction
Features
• Remote Intelligent Analog Output and Digital I/O Units with Opto-Isolated RS485 Serial
Interface to Host Computer
• Eight 12-Bit Analog Current Sinks (4-20mA) and Voltage Outputs
• Software Selectable Voltage Ranges of 0-5V, 0-10V, ±5V
•
Low-Power and High-Power Analog Output Models
•
Seven Bits of Digital I/O Configured on a Bit-by-Bit Basis as either Inputs or High-
Current Outputs
•
Field Connections Accomplished via 50-pin Removable Screw Terminals
•
Onboard 16-bit 8031 Compatible Microcontroller
• All Programming and Calibration in Software, No Switches to Set. Jumpers Available to
By-Pass Opto-Isolators if Desired
• Protective Metal T-Box included
Description
RDAG12-8 is an intelligent, 8-channel, digital-to-analog converter unit that communicates with the
host computer via EIA RS-485, Half-Duplex, serial communications standard. ASCII-based
command/response protocol permits communication with virtually any computer system.
RDAG12-8 is one of a series of remote intelligent Pods called the "REMOTE ACCES Series". As
many as 32 REMOTE ACCES Series Pods (or other RS485 devices) may be connected on a single
two or four-wire multidrop RS485 network. RS485 repeaters may be used to extend the number of
Pods on a network. Each unit has a unique address. Communication uses a master/slave protocol
wherein the Pod talks only if questioned by the computer.
An 80C310 Dallas microcontroller (with 32k x 8 bits RAM, 32K bits non-volatile EEPROM, and
a watchdog timer circuit) gives RDAG12-8 the capability and versatility expected from a modern
distributed control system. RDAG12-8 contains CMOS low-power circuitry, an optically-isolated
receiver/transmitter, and power conditioners for local and external isolated power. It can operate
at baud rates up to 57.6 Kbaud and distances up to 4000 feet with low-attenuation twisted-pair
cabling, such as Belden #9841 or equivalent. Data collected by the Pod can be stored in local RAM
and accessed later through the computer's serial port. This facilitates a stand-alone Pod mode of
operation.
All programming of RDAG12-8 is in ASCII-based software. ASCII-based programming permits you
to write applications in any high-level language that supports ASCII string functions.
The module, or Pod, address is programmable from 00 to FF hex and whatever address is assigned
is stored in EEPROM and used as the default address at the next Power-ON. Similarly, the baud rate
is programmable for 1200, 2400, 4800, 9600, 14400, 19200, 28800, and 57600. The baud rate is
stored in EEPROM and used as default at the next Power-ON.
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Manual MRDAG12-8H.Bc2