Advantech Adam-4012 User Manual

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E-2 ADAM 4000 Series User's Manual

RS-485 Network

ADAM modules are fully isolated and use just a single set of twisted pair

wires to send and receive! Since the nodes are connected in parallel they

can be freely disconnected from the host without affecting the functioning

of the remaining nodes. In industry shielded twisted pair is preferable due

to the high noise ratio of the environment.

When nodes communicate through the network, no sending conflicts can

occur since a simple command/response sequence is used. There is always

one initiator (with no address) and many slaves (with address). In this case

the master is a personal computer that is connected with its serial, RS-232,

port to an ADAM RS-232/RS-485 converter. The slaves are the ADAM I/

O modules. When modules are not transmitting data, they are in listen

mode. The host computer initiates a command/response sequence with one

of the modules. Commands normally contain the address of the module the

host wants to communicate with. The module with the matching address

carries out the command and sends its response to the host.

E.1 Basic Network Layout

Multi-drop RS-485 implies that there are two main wires in an segment.

The connected modules tap from these two lines with so called drop cables.

Thus all connections are parallel and connecting or disconnecting of a node

doesn’t affect the network as a whole. Since ADAM modules use the RS-

485 standard, and use an ASCII-based commands set, they can connect and

communicate with all ASCII-based computers and terminals. The basic

layouts that can be used for an RS-485 network are:

Daisychain

The last module of a segment is a repeater. It is directly connected to the

main-wires thereby ending the first segment and starting the next segment.

Up to 32 addressable modules can be diasychained . This limitation is a

physical one. When using more modules per segment the IC driver current

rapidly decreases, causing communication errors. Totally the network can

hold up to 256 addressable modules. The limitations for this number is the

two number hexadecimal address code that knows 256 combinations. The

ADAM converter, ADAM repeaters and the host computer are non

addressable units and therefore are not included in these numbers.

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Advantech Adam-4012 Specifications

General

Type	Analog Input Module
Channels	8
Resolution	16-bit
Communication	RS-485
Protocol	Modbus RTU
Power Supply	10-30 VDC
Isolation Voltage	3000 VDC
Input Range	4-20 mA
Sampling Rate	10 samples per second (per channel)
Operating Temperature	-10°C to +60°C (14°F to 140°F)
Accuracy	±0.1% of FSR
Storage Temperature	-40 to 85 °C
Humidity	10 to 90% RH

Summary

Introduction

Overview of ADAM Series Modules

Describes the intelligent sensor-to-computer interface modules, their remote control via RS-485, and key functions like signal conditioning and A/D conversion.