ANALOG DEVICES UG-181 Service Manual

PLC Demo System User Guide

A

UG-181

One Technology Way • P. O . Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel : [phone] • Fax : [phone] • www.analog.com

PLC Demo System, Industrial Process Control Demo System

FEATURES

EMC performance tested
Inputs selectable: 0 mA to 20 mA, 4 mA to 20 mA, 0 V to 5 V,

0 V to 10 V, ±5 V, ± 10 V, R TD, TC

Outputs programmable: 0 mA to 20 mA, 0 mA to 24 mA,

4 mA to 20 mA, 0 V to 5 V, 0 V to 10 V, ±5 V, ±10 V

Four isolated 24-bit analog input channels

AD7793 24-bit sigma-delta (Σ-Δ) ADC, 40 nV noise
AD8220 instrumentation amplifier, >80 dB CMRR
ADuM5401 isoPower® integrated, isolated dc-to-dc

converter, 500 mW output power

ADR441 precision 2.5 V reference

4 isolated 16-bit analog output channels

AD5422 single-channel, 16-bit, serial input, current source

and voltage output DAC

0.01% typical total unadjusted error (TUE)
Single chip solution
Output fault detection and protection

Power/interface/control

Analog Devices, Inc., ARM7 ADuC7027

ADP1715 500 mA low-dropout CMOS linear regulator

ADM3251E isolated single-channel RS-232 line

driver/receiver

APPLICATIONS

Process control
Transmitters
Actuator control
PLC/DCS systems

GENERAL DESCRIPTION

The PLC demonstration system is aimed at demonstrating the
value Analog Devices parts can add to a PLC system. The demo

board contains four fully isolated ADC channels, a micro­processor with RS-232 interface and four fully isolated DAC
output channels.

Input ranges are hardware programmable and include 0 V to
5 V, 0 V to 10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA,
±20 mA, thermocouple and RTD. Output ranges are software
programmable and include 0 V to 5 V, 0 V to 10 V, ±5 V,
±10 V, 4 mA to 20 mA, 0 mA to 20 mA, and 0 mA to 24 mA.

The PLC demo system features the AD5422 (a single-chip
16-bit DAC solution with ±0.05% TUE) and AD7793 (low
noise, low power, 24-bit Σ-Δ ADC). Isolation is achieved using
the ADuM5401 (quad-channel isolator with integrated dc-to­dc converter), ADuM1401 (quad-channel isolator), or

ADM3251E (fully isolated RS-232 transceiver).

Input signal conditioning is performed by the AD8220 (>80 dB
CMRR, JFET in-amp). Voltage references include the ADR441,

ADR445 (ultralow noise, XFET® voltage reference), and
ADP1720 (50 mA, high voltage, micropower linear regulator).

Communications with the ADC and DAC channels take place
using the ADuC7027 microcontroller, which can be connected
to a PC via an isolated RS-232 interface.

NALOG SIGNALS

SENSOR INPUTS

• RTD

• TC

• GAS

VOLTAGE INPUTS
(FLOW, PRESSURE)

• 0V TO 5V, 0V TO 10V

• ±5V, ±10V

CURRENT INPUTS
(COMMU NICATIONS)

• 0mA TO 20mA

• 4mA TO 20mA

Figure 1. PLC System Level Diagram

PLC

MODULE

BOARD

ANALOG OUTPUTS

VOLTAGE OUTPUTS

• 0V TO 5V, 0V TO 10V

• ±5V, ±10V

CURRENT OUTPUTS

• 0mA TO 20mA

• 0mA TO 24mA

• 4mA TO 20mA

09257-001

09257-002

Figure 2. PLC Demo Board

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.

Rev. 0 | Page 1 of 16

UG-181 PLC Demo System User Guide

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

PLC Total Solution Diagram ........................................................... 3

Demo Systems Hardware ................................................................. 4

Inputs ............................................................................................. 4

Outputs .......................................................................................... 5

REVISION HISTORY

8/10—Revision 0: Initial Version

Power Supplies ...............................................................................6

RS-232 Communications .............................................................6

Demo System Software .....................................................................7

Software Installation .....................................................................7

Software Operation .......................................................................7

Firmware .........................................................................................9

EMC Test Results ............................................................................ 10

Simplified Input/Output circuit Diagrams ................................. 11

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PLC Demo System User Guide UG-181

PLC TOTAL SOLUTION DIAGRAM

V/I INPUT S, BIPOLAR SUPPLY, HIGH PERF ORMANCE

±15V

ADR441

AD8220

V/I INPUTS, SINGLE SUPPLY, LO WER COST

IOUT1

IOUT2

ADR441

IOUT1

ADP1720

2.5V 5V

AD7793

2.5V 5V

±15V
ISOLATED
DC-TO-DC

ADuM1401

ISOLATED

ADuM5401

24V

5V

SPI

ADP1715

3.3V

5V

ISO DC-TO-DC

ADuM1401

ISOLATED

ADR445

AD5422

DAC

SPI

24V

(>30mA)

±15V
ISOLATED
DC-TO-DC

OPEN

DETECT

I

OUT

RANGE
SCALE

V

OUT

RANGE
SCALE

OVERTEMP

DETECT

4mA TO 20mA,
0mA TO 24mA

0V TO 5V,
0V TO 10V,
±5V, ±10V

AD8220

IOUT2

AD7793

TX/RX

ISOLATED

ADM3251E
ISOLATED

RS-232

5V

3.3V

ADuC7027

AD5422

ADuM1401

DAC

SPI

ISOLATED

(>30mA)

±15V
ISOLATED
DC-TO-DC

OPEN

DETECT

I

OUT

RANGE
SCALE

V

OUT

RANGE
SCALE

OVERTEMP

DETECT

4mA TO 20mA,
0mA TO 24mA

0V TO 5V,
0V TO 10V,
±5V, ±10V

09257-003

Figure 3. PLC Block Diagram

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UG-181 PLC Demo System User Guide

DEMO SYSTEMS HARDWARE

Figure 4 shows the locations of the various functional blocks of
the PLC demo system.

OUTPUT 4

INPUT 4

OUTPUT 3

Input Connectors

Each input channel contains three sets of connectors; Jx1
connectors for voltage and current inputs, Jx2 connectors for
thermocouple inputs, and Jx3 for RTD inputs (see Figure 6).
Although all the channels allow for all three input types, the
PLC demo software limits the inputs as described in Table 2.

INPUT 3

INPUT 2

INPUT 1

Figure 4. Channel Locations

OUTPUT 2

OUTPUT 1

09257-004

INPUTS

DIP switches on the PLC demo board must be set to configure
each input channel to the required input range. These switches
are found to the left of each input channel’s circuitry. Figure 5
shows a diagram of these switches, and Tab le 1 lists the required
switch configurations for each input range.

1

2

3

4

5

6

7

8

Figure 5. Input Channel Switches

Table 1. Input Channel Switch Settings

Range

Switch
No.

0 V to 5 V,
±5 V

0 V to 10 V,
±10 V

1 On Off On Off Off
2 Off Off Off Off Off
3 Off Off On Off Off
4 On On On Off Off
5 On On On Off Off
6 On On On Off Off
7 Off Off Off On Off
8 Off Off Off On Off

ON

Current

9257-005

Thermo­couple RTD

–

VOLTAGE AND CURRENT INPUTS
0V TO 5V, 0V TO 10V, ±5V, ±10V

Jx1

0mA TO 20mA, 4mA TO 20mA, ±20mA

+

–

THERMOCOUPL E INPUT

Jx2Jx3

+

I

OUT2

I

3-WIRE RTD I NPUT

OUT1

REF

Figure 6. Input Connectors

09257-006

Table 2. Ranges Allowed in PLC Demo Software

Input Channel Input Type

1 JA1—voltage and current (unipolar)
2 JB2—thermocouple
3 JC1—voltage and current (bipolar)
4 JD3—RTD

Voltage and Current

The JA1 and JC1 connectors allow for various signaling inputs
(see Figure 6). JA1 (Channel 1) allows for single-ended unipolar
inputs: 0 V to 5 V, 0 V to 10 V, 4 mA to 20 mA, and 0 mA to
20 mA. Figure 20 shows a circuit diagram of this input. JC1
(Channel 3) allows for differential inputs: 0 V to 5 V, 0 V to
10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA, and
±20 mA. Figure 21 shows a circuit diagram of this input. To
set the input range switches, see Tabl e 1.

The 250 Ω current sensing resistor on the input channels has a
25 ppm/°C drift specification. The user can observe the drift
from this resistor and can chose to replace this with a lower
drift resistor if greater performance is desired.

Rev. 0 | Page 4 of 16

PLC Demo System User Guide UG-181

Thermocouple

JB2 (Channel 2) is for thermocouple inputs (see Figure 6).
Figure 22 shows a circuit diagram of this input. The PLC
software allows the user to connect many different thermo­couple types including J-, K-, and T-types. To set the input
range switches for thermocouple inputs, see Tab l e 1.

The PLC demo system hardware comes with a T-type
thermocouple. Figure 7 shows how to connect this
thermocouple to the PLC demo board.

OUTPUTS

Each output channel contains both a current and a voltage
output connector. The relevant connectors are +VOUT/GND
and IOUT/GND (Figure 9). The available output ranges are 0 V
to 5 V, 0 V to 10 V, ±5 V, ±10 V, 4 mA to 20 mA, 0 mA to 20 mA,
and 0 mA to 24 mA. On each channel, either the voltage or
the current output can be enabled. The output that is not in
use is tristated. If neither channel is enabled both are tristated.
Figure 24 shows a circuit diagram of the output channels.

09257-007

Figure 7. Thermocouple Connector

RTD

JD3 (Channel 4) is for 3-wire RTD inputs (see Figure 6).
Figure 23 shows a circuit diagram for these inputs. To set
the input range switches for 3-wire RTD inputs, see Ta ble 1 .

The PLC demo system hardware comes with a PT1000 RTD
temperature sensor. Figure 8 shows how to connect this RTD
to the PLC demo board.

OPTIONAL 32V INPUT

TO INCREASE THE VOLTAGE

COMPLIANCE LIMIT ON THE

CURRENT OUTPUT

VOLTAGE OUTPUT

0V TO 5V,

0V TO 10V,

±5V, ±10V

CURRENT OUTPUT

0mA TO 20mA,
4mA TO 20mA,

0mA TO 24mA

+32VDC

GND

+VOUT

GND

IOUT

GND

09257-009

Figure 9. Output Connectors

Increasing the Output Compliance

The voltage compliance limit on the current output is 12.5 V.
A connector is available to externally provide 32 V dc, which
increases the output compliance to 29.5 V. The relevant
connectors are labeled +32VDC and GND (see Figure 9).
Figure 10 shows how +32VDC is connected to the channel
supply of the AD5422. There is a 20 V TVS on the I

, which

OUT

may need to be changed/removed if an external supply is used.

+15V

ISO

+32VDC

GND

Figure 8. RTD Connection

–15V

ISO

V

V

DD

SS

V

I

OUT

OUT

I

OUT

GND

09257-010

AD5422

Figure 10. +32VDC Connection on the Output Channels

09257-008

Rev. 0 | Page 5 of 16