Watlow 988, 989 Data sheet

SERIES 988/989

The Series 988/989
Offers More
Features, Greater
Versatility
Than Any Other

1

⁄8 DIN Control

Watlow’s Series 988/989 is truly an innovation in the control
field. The Series 988/989 is the first to combine so many key
features into a single, 1⁄8 DIN size package. No other control
offers the flexibility, compact size and durability of the
Series 988/989.

This control meets a wide variety of needs in the process
industries. Its broad range of I/O options allows control of
virtually any process variable.

From the long list of product features, the Series 988/989’s
ability to provide single unit cascade control of a process is
perhaps the most unique. The Series 988/989 is the only

1

⁄

8 DIN

control with this feature. Other features include heater current
monitoring, remote set point input, differential or ratio control.
Valve control via slidewire feedback is another popular feature.

The Series 988/989 has all the standard characteristics you
expect from a Watlow control and more. We expanded the
auto-tuning capabilities and increased the alarm functionality.
The Series 988/989 offers several unique control algorithms.

The Series 988/989 features a three-year warranty and four day
shipment on all model numbers in limited quantities.

Your Authorized Watlow Distributor is:

Windows®is a registered trademark of Microsoft Corporation.
Modbus™ is a trademark of AEG Schneider Automation.

1241 Bundy Boulevard, P.O. Box 5580
Winona, Minnesota 55987-5580 USA
Phone: [phone]
Fax: [phone]
Internet: www.watlow.com
e-mail: [e-mail]

WIN-988/989-0603

© 2003 Watlow Electric Manufacturing Company Printed in the USA on Recycled Paper, 15% Postconsumer Waste

Features and Benefits

Two universal analog inputs and one event input

• Provides greater application versatility

Compact size 103 mm (4.06 in.) behind panel depth

• Fits easily in confined areas

10Hz sampling rate

• Improves control

Windows

®

configuration software and Modbus™ serial

communications

• Offers remote operation

Slidewire feedback input

• Monitors valve position and offers precision control

Burst firing output

• Provides smooth process control

Signal conditioner power supply

• Eliminates the need for an external drive

NEMA 4X front panel

• Provides watertight and corrision resistance

ISO 9001

ISO 9001

Registered Company

Winona, Minnesota USA

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MODE

AUTO

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SERIES 988

Analog
Input 1

Analog
Input 2

4-20mA Valve Control Output

Material A
Controlled Stream

Material B
Wild Stream

Material C
Mixed Material

Flow Sensor

Flow Sensor

Ratio Control

Whether mixing materials or controlling
temperature indirectly, ratio control with
the Series 988/989 provides automatic set
point adjustments in response to
system changes.

• Simplified process control; one control does

the work of two

• Low cost solution; one control,

display access - both process variables

• One control for many applications

• Easy set-up; increased operator productivity

Product Highlights

Easy to Operate

The Series 988/989’s operator interface features the simplicity
you expect from a Watlow control. The display key allows the
operator to view information pertinent to the process,
including deviation from set point, percent output and units
of measurement.

The display key also returns the operator to the process
and set point display from anywhere in the menu system.
The setup menu is segmented into input, output, global and
communication parameters, allowing movement forward or
backward throughout the parameter sequence.

Use Up To Four Outputs

The control can have up to four outputs total, including the
standard Watlow output options, along with retransmit and
communications. Up to three outputs can be defined as a
power supply output to power external signal conditioners,
eliminating the need for an external power supply. The output
types are recognized by the control to simplify control setup
and operation, with no need for DIP switches.

Three Inputs Allow Greater Flexibility

To accommodate unique system configurations, the Series
988/989 offers two universal analog inputs and one event
(digital) input. The analog input applications are explained in
detail below. The event input allows the operator to select a
function at the close of a switch. This can lock out the front
panel, switch PID values, go to a remote or second set point,
etc. The inputs are optically isolated from all outputs,
eliminating the need for external isolation circuitry.

Cascade Control

Cascade control provides precise,
two-variable process control.
By measuring the secondary
variable, the control can
"feed forward," and automatically
determine the primary variable set point.

• Precise control via cascade configuration

• Display of both process variables

• Low cost; one unit does the work of two

• Increased operator productivity with fast set-up

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SERIES 988

Input 1

Input 2

Slide Wire Feedback / Position Sensor

Thermocouple

CCW - Open

CW - Close

Slidewire Feedback Valve Control

Valve positioning feedback
(% open, % close) provides precise
process control. The Series 988/989 is
configurable for a wide variety of valves.

• Accepts virtually any valve input

• Front panel valve position display

• Increased valve life with anti-hunting parameter

• Greater process efficiency with precise control

• Easy set-up; increased operator productivity

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Input 1

Input 2

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SERIES 988

Outer-Loop
Thermocouple

W

A

TL

Output 1

DISPLAY

AUTO
MAN

MODE

Limit

Limit Sensor

Oil In

Heater

Lube Oil Ta nk

Oil Out

Inner-Loop
Thermocouple