Honeywell DirectLine DL421 User manual

Industrial Measurement and Control
DirectLine® DL421 Sensor Module
for Durafet®II, Durafet®III,
Meredian® II, and HPW7000 pH
Electrodes
User Manual
70-82-25-102
Rev. 5
2/04

ii DirectLine® DL421 Sensor Module User Manual 2/04
Notices and Trademarks
Copyright 2004byHoneywell
February, 2004
Warranty/Remedy
Honeywell warrants goods of its manufacture as being free of defective materials and faulty
workmanship. Contact your local sales office for warranty information. If warranted goods are returned to
Honeywell during the period of coverage, Honeywell will repair or replace without charge those items it
finds defective. The foregoing is Buyer's sole remedy and is in lieu of all other warranties, expressed or
implied, including those of merchantability and fitness for a particular purpose. Specifications may
change without notice. The information we supply is believed to be accurate and reliable as of this
printing. However, we assume no responsibility for its use.
While we provide application assistance personally, through our literature and the Honeywell web site, it
is up to the customer to determine the suitability of the product in the application.
CE Conformity
This product is in conformance with the protection requirements of the following European Council
Directives: 89/336/EEC, the Electromagnetic Compatibility Directive and 73/23/EEC, the Low Voltage
Directive. Conformance of this product with any other “CE Mark” Directive(s) shall not be assumed.
ATTENTION
The emission limits of EN 61326 are designed to provide reasonable protection against harmful
interference when this equipment is operated in an industrial environment. Operation of this equipment in
a residential area may cause harmful interference. This equipment generates, uses and can radiate radio
frequency energy and may cause interference to radio and television reception when the equipment is
used closer than 30 m to the antenna(e). In special cases, when highly susceptible apparatus is used in
close proximity, the user may have to employ additional mitigating measures to further reduce the
electromagnetic emissions of this equipment.
Industrial Measurement and Control
Honeywell
1100 Virginia Ave.
Fort Washington, PA 19034
DirectLine is a registered trademark of Honeywell
Durafet and Meredian are U.S. registered trademarks of Honeywell
Other brands or product names are trademarks of their respective owners
Insert 70-82-10-01 should accompany this document.

2/04 DirectLine® DL421 Sensor Module User Manual iii
About This Document
Abstract
This manual contains all the information that is needed to install, configure, calibrate,
operate, and troubleshoot the DirectLine® Sensor. Insert 70-82-10-01, a quick
reference guide for configuring and calibrating the DL421, should accompany this
document.
Contacts
World Wide Web
The following lists Honeywell’s World Wide Web sites that will be of interest to our
customers.
Honeywell Organization WWW Address (URL)
Corporate http://www.honeywell.com
Industrial Measurement and Control http://www.honeywell.com/imc
International http://www.honeywell.com/Business/global.asp
Telephone
Contact us by telephone at the numbers listed below.
Organization Phone Number
United States and
Canada
Honeywell 1-800-423-9883
[phone] Tech. Support
1-888-423-9883 Q&A Faxback
(TACFACS)
1-800-525-7439 Service
Symbol Definitions
The following table lists any symbols used in this document to denote certain conditions.
Symbol Definition
Earth Ground. Functional earth connection. NOTE: This connection shall be bonded to
Protective earth at the source of supply in accordance with national and local electrical
code requirements.
ATTENTION, Electrostatic Discharge (ESD) hazards. Observe precautions for handling
electrostatic sensitive devices

iv DirectLine® DL421 Sensor Module User Manual 2/04
Contents
1. INTRODUCTION....................................................................................................................1
1.1 Overview......................................................................................................................................... 1
1.2 Electronics Module ......................................................................................................................... 1
1.3 Operator Interface........................................................................................................................... 2
1.4 Specifications.................................................................................................................................. 3
1.5 Model Selection Guide ................................................................................................................... 4
2. INSTALLATION ..................................................................................................................... 5
2.1 Assembly and Wiring...................................................................................................................... 5
2.2 Integral Mounting............................................................................................................................ 7
2.3 Remote Mounting ........................................................................................................................... 8
2.4 Conduit connections ..................................................................................................................... 13
3. CONFIGURATION ............................................................................................................... 14
3.1 Overview....................................................................................................................................... 14
3.2 Configuration Set Up Procedure................................................................................................... 15
4. CALIBRATION.....................................................................................................................18
4.1 Calibration Diagnostics................................................................................................................. 18
4.2 Calibration Diagnostic Reset ........................................................................................................ 18
4.3 Calibration..................................................................................................................................... 19
4.4 Calibration in High Purity Water ................................................................................................... 22
5. OPERATION ........................................................................................................................ 23
5.1 Displays ........................................................................................................................................ 23
5.2 Diagnostic Error Messages .......................................................................................................... 25
5.3 Unit Reset ..................................................................................................................................... 26
6. SPARE PARTS....................................................................................................................27
7. APPENDIX: CE MARK APPLICATIONS ............................................................................ 30
8. SALES AND SERVICE ........................................................................................................ 32

2/04 DirectLine® DL421 Sensor Module User Manual v
Tables
Table 2-1 Assembly and Wiring Procedure for Field Wiring Connector___________________________ 6
Table 2-2 Integral Mounting Procedure (refer to Figure 2-3) __________________________________ 7
Table 2-3 Remote Mounting Procedure for Durafet II and Durafet III Electrodes __________________ 8
Table 2-4 Remote Mounting Procedure for Meredian II Electrodes_____________________________ 9
Table 2-5 Remote Mounting Procedure for HPW7000 Electrodes ____________________________ 10
Table 3-1 Buffer Groups and the pH standard values ______________________________________ 14
Table 3-2 Configuration Set Up Procedure ______________________________________________ 15
Table 4-1 Standard pH Buffer Values __________________________________________________ 20
Table 4-2 Zero (Standardization) Calibration Procedure ____________________________________ 21
Table 4-3 Slope Calibration Procedure _________________________________________________ 22
Table 4-4 High purity water calibration Procedure_________________________________________ 22
Table 5-1 Online Parameter Descriptions _______________________________________________ 23
Table 5-2 Display Navigation Procedure ________________________________________________ 24
Table 5-3 Online Diagnostic Errors ____________________________________________________ 25
Table 5-4 Factory Default Values _____________________________________________________ 26

vi DirectLine® DL421 Sensor Module User Manual 2/04
Figures
Figure 1-1 DirectLine® Sensor ________________________________________________________ 1
Figure 1-2 Electronics Module _________________________________________________________ 2
Figure 2-1 Cordset Connection and Wiring ________________________________________________ 5
Figure 2-2 Field Wiring Connector______________________________________________________ 6
Figure 2-3 Integral Mounting __________________________________________________________ 7
Figure 2-4 Remote Mounting _________________________________________________________ 11
Figure 2-5 Remote Mounting Hardware_________________________________________________ 12
Figure 7-1 Wiring for CE Mark Applications______________________________________________ 30

Introduction
2/04 DirectLine® DL421 Sensor Module User Manual 1
1. Introduction
1.1 Overview
The DirectLine® Sensor consists of an electronics module connected to a
Durafet® II, Durafet® III, Meredian® II or HPW7000 pH electrode that eliminates
the need for pre-amps, transmitters, and analyzers in pH applications.
The modular electronics design can be separated from the sensor, allowing the
sensor to be easily removed or replaced while retaining power to the electronics
module.
The DL421 electronics module is contained in a Nema Type 4x polysulfone
housing. The Module can be mounted as an integral unit directly connected to the
electrode or remotely using an electrode with a cable. The sealed plastic housing
has plug-in connections for the pH electrode and 4-20 mA cordset.
Figure 1-1 DirectLine® Sensor
1.2 Electronics Module
The electronics module is loop-powered by 16-42 Vdc and will modulate its supply
current from 4 mA to 20 mA, depending upon the pH value that is sensed by the
electrode. The transmitted loop current is compensated for temperature internally
using the standard Honeywell 8550 thermistor.
For submersion or special wiring applications, the remote electronics module is
compatible with the existing Durafet II, Meredian II or HPW7000 technology without
modification. A Durafet II or Meredian II cable length is supported with direct
connection to the electronics module.
A 4-20 mA output connection is provided via a 6m cordset or a customer supplied
cable used in combination with a field wiring connector.

Introduction
2 DirectLine® DL421 Sensor Module User Manual 2/04
Figure 1-2 Electronics Module
1.3 Operator Interface
The DirectLine® Sensor operator interface consists of three pushbuttons and one 4-
digit, 7-segment LCD display with 3 decimal points, plus (+), and minus (–) signs. It
is responsible for the display of measured values and configuration of parameter
values.

Introduction
2/04 DirectLine® DL421 Sensor Module User Manual 3
1.4 Specifications
Displayed pH 0-14 pH
Displayed Temperature Range –10 °C to +110 °C (14 °F to 230 °F)
Process Temperature –10 °C to +110 °C (14 °F to 230 °F)
Sensor Survivable Temperature Range
DurafetII & III
Meredian II
–10 °C to +130 °C (14 °F to 266 °F)
0 °C to 110 °C (32 °F to 230 °F)
Electronics Module Ambient Temperature –20 °Cto +85 °C (–4 °F to +185 °F)
Output Type 4-20 mA (2-wire loop powered)
Output Scale 0-14 pH
Output Calibration 4-20 mA
Mating Connector Rating Submersible to 6.1m (20’)
Output (Loop) 6m (19.7’) cordset or Shielded twisted pair with field
wiring connector
User Termination Tinned leads
Cable Lengths
Sensor: Durafet II & Durafet III: 6.1m (20’) or 15.24m (50’)
Meredian II: 3.65m (12’) or 6.1m (20’)
HPW7000: .45m (1.5’) or 10.97m (36’)
Power 16-42 Vdc, 23mA max
Maximum load resistance: 250 ohms at 16 Vdc
600 ohms at 24 Vdc
1400 ohms at 42 Vdc
Local Display and Buttons LCD 4-digit, 7-segment
Engineering Units pH
degrees F
degrees C
Calibration Options 1 point Sample or 2 point Sample
Auto Buffer Recognition
Selections: US, NIST, EURO
Solution Temperature Compensation Selections: 0.00pH/10°C
–0.16pH/10°C
–0.32pH/10°C
Diagnostics Sensor and electronics
Case Weatherproof, corrosion-resistant plastic housing, NEMA4X
Approvals CE Mark for Industrial Applications
UL – General Purpose for Process Control
CSA – General Purpose
FM – CLI, DIV1, Groups A, B, C & D and CLI, Zone 0
AEx ia IIC (IS)
FM – CLI, DIV2, Groups A, B, C & D and CLI, Zone 2,
Groups IIC (N.I. Field Wiring)
Remote Mounting Pipe, Wall, or DIN Rail
Dimensions H 123 mm (4.84”) x W 48 mm (1.89”) x D 46 mm (1.81”)
Weight Approximately 142 g (5.0 oz.)

Introduction
4 DirectLine® DL421 Sensor Module User Manual 2/04
1.5 Model Selection Guide
Instructions
Select the desired key number. The arrow to the right marks the selection available.
Make the desired selections from Tables I through IV using the column below the
proper arrow. A dot ( ) denotes availability.
Key Number I II III IV
_ _ _ _ _ -
_
-
_
-
_
-____
Key Number - DirectLine
®
Sensor Electronics Module
(Specify electrodes/cells/probes separately) Selection
pH For use with Durafet II, Meredian II & HPW7000 pH electrodes DL421
ORP For use with ORP electrode DL422
Conductivity For use with Contacting Conductivity Cells DL423
DO - PPM For use with Dissolved Oxygen ppm Probes DL424
DO - PPB For use with Dissolved Oxygen ppb Probes
TABLE I - OUTPUT CABLE
Cordset - 6m (19.7 ft.) - includes connector and cable - Note 2 E
Field Wiring Connector only - customer supplies cable only - Note 2
TABLE II - SENSOR CABLE/REMOTE CONNECTOR (between electronic module and electrode, sensor or probe)
Integral Mounting 0ddddd
Remote Mounting 6,096m (20 ft.) of sensor cable - Durafet II Remote Mtg w/PWB connector 1e
Cable - 6,096m (20 ft.) of sensor cable-Durafet III Remote Mtg w/Vario Pin connector-Note 3 7e
Durafet Onl
y
15,24m (50 ft.) of sensor cable - Durafet II Remote Mtg w/PWB connector e
15,24m (50 ft.) of sensor cable - Durafet III Remote Mtg w/Vario Pin connector-Note 3 e
Remote Mounting Remote Mounting Connector - Meredian II pH e
Connector (Cable Remote Mounting Connector - Meredian II ORP e
is supplied with Remote Mounting Connector - HPW7000 e
sensor or probe) Remote Mounting Connector - Conductivity e
Remote Mounting Connector - Dissolved Oxygen ee
TABLE III - REMOTE MOUNTING OPTIONS
Mounting Kit for None Integral unit - mounting not required A
Remote Mounting 2" (5,08 cm) Pipe mtg. bracket, wall mtg, & DIN Rail clip B
TABLE IV - OPTIONS
Tagging None 00 _ _
SS Customer ID Tag - 3 lines w/22 characters/line SS _ _
Certificates None _ _ 00
Calibration & Conformance _ _ CC
3
3
No cable or connector required
Mounting F
None (replacement module or customer supplied output cable)-Note 1
4
5
6
Availability
Output Cable for
Integral or Remote
DL425
D
2
8
Notes:
1Customers may procure their own output cordsets from the vendors listed below.
2Customers may make their own 4-20 mA output cordset using a 2-wire twisted shielded pair,
and M12 field wiring connector procured from one of the vendors listed below.
Use only UV rated outdoor cable to maintain NEMA 4 rating.
Phoenix Contact Turck
Cordset SAC-3P-5.0-PUR/M12FSSH Stainless RKV4T-6/S618
M12 Field Wiring Connector SACC-M12FS-4CON-PG7 B8141-0
Cable
3Durafet III cables with Vario Pin connector require Durafet III electrode with Vario Pin connector
RESTRICTIONS
Table
d
e
ORDERING INSTRUCTIONS:
1. Part numbers are provided to facilitate Distributor Stock.
2. Orders may be placed either by model selection or by part number.
3. Part numbers are shown within the model selection tables to assist with compatibility information.
4. Orders placed by model selection are systematically protected against incompatibility.
5. Compatibility assessment is the responsibility of the purchaser for orders placed by part number.
6. Items labeled as N/A are not available via the stocking program and must be ordered by model selection.
2-wire twisted shielded pair
Restriction
Letters SelectionSelection
III B
Available Only With Not Available With
IIl A
Table

Installation
2/04 DirectLine® DL421 Sensor Module User Manual 5
2. Installation
2.1 Assembly and Wiring
Depending on the customer selected output cable options, the DirectLine can be
wired to an appropriate 16-42 Vdc source using 2 different methods:
1) cordset
2) field wiring with customer supplied cable.
Refer to Section 7 for wiring for CE Mark applications.
2.1.1 Cordset
Electronics
Module
Black (–)
Brown (+)
Shield
Wire
(Ground)
Minimum: 16 V @ 250 ohms (max.)
Maximum: 42 V @ 1400 ohms (max.)
Power Supply
++
__
Load
Resistance
+
_
Chart Recorder,
Controller, etc.
(Use 250 ohms
for 1-5 V signal) Cordset 6m (19.7’)
*Blue wire not used
*
Figure 2-1 Cordset Connection and Wiring

Installation
6 DirectLine® DL421 Sensor Module User Manual 2/04
2.1.2 Field Wiring
Refer to Figure 2-2. The field wiring connector supports customer supplied cable with an
outer diameter of 4-6mm.
Table 2-1 Assembly and Wiring Procedure for Field Wiring Connector
Step Procedure
1 Disassemble field wiring connector
a) Unscrew parts to separate pressure screw, clamp type cage, gasket,
housing and female insert.
2 Insert customer supplied cable through connector parts
a) Slide pressure screw over skin and tinned customer cable (note
orientation).
b) Slide clamp type cage over cable (note orientation).
c) Slide gasket over cable.
d) Slide housing over cable (note orientation).
3 Connect wires to pins
Look closely at end of female insert to locate pin numbers. Connect
positive wire to pin 1 and negative wire to pin 4. Remaining wires and
female insert pins 3 and 2 are unused.
4 Assemble field wiring connector
a) Screw female insert to housing until female insert’s o-ring is
compressed.
b) Slide clamp type cage/gasket into housing.
c) Thread pressure screw into housing until ¼ turn past finger tight.
5 Connect cable to source
Wire the other end of the Output cable to a 16-42 Vdc source as indicated
in Figure 2-1. Note: your wire colors may be different.
Pressure screw
Clamp-type cage
Gasket
Housing
Female insert with 4
numbered pins
Pos +
Neg -
To Power Supply
Output cable
(Customer supplied)
Figure 2-2 Field Wiring Connector

Installation
2/04 DirectLine® DL421 Sensor Module User Manual 7
2.2 Integral Mounting
Table 2-2 Integral Mounting Procedure (refer to Figure 2-3)
Step Procedure
Connect Electrode to Pipe and Electronics Assembly
1 Screw the electrode into the pipe tee (3/4 “ NPT thread).
Make sure that the final position of the installed electronics module allows the display to
be easily viewed by plant personnel.
2 Align the slots in the electronics module with those in the electrode and press down to
connect the electronics to the electrode.
3 Tighten the locking screw on the bottom rear of the electronics module.
Electronics
Module
Locking Screw in
Rear of Housing
Electrode
Step 1
Step 2 Step 3
Figure 2-3 Integral Mounting

Installation
8 DirectLine® DL421 Sensor Module User Manual 2/04
2.3 Remote Mounting
Table 2-3 Remote Mounting Procedure for Durafet II and Durafet III Electrodes
Step Procedure (Refer to Figure 2-4 and Figure 2-5)
1 Apply a thin film of silicon grease to the ID of electronics module’s remote mounting
cavity.
2 Connect Remote Sensor Wiring Cable to the Remote Electronics Housing
a) Remove the cover from the remote cable connector.
b) Align the slots in the cable connector housing with those in the electronics module
and push up to connect the cable to the electronics module.
c) Tighten the locking screw on the rear of the electronics module. Make sure the
connector is completely seated.
3 Secure Electronics Module with Wall, Pipe, or DIN Rail Mounting
Mount bracket with clips facing forward, smaller clip on top and larger clip on bottom.
Wall: Use one of three through-holes to secure to wall.
Pipe: Feed hose clamp through two slots and secure to pipe.
DIN rail: Attach the appropriate DIN rail clip to the mounting bracket:
“U” DIN rail—use metal clip and shorter screw (8 mm)
“G” DIN rail—use gray clip and longer screw (10 mm)
Clip can be rotated for horizontal or vertical DIN rails.
Push electronics module onto the remote mounting bracket until it snaps into position.
4 Connect Remote Sensor Wiring Cable to the Remotely Mounted Electrode
Durafet II with PC Board type connector:
a) Remove cover from the remote cable connector.
b) Loosen the ferrule and slide back the ferrule, small O-ring, and plastic cover to
expose the remote cable connector. Align the cable connector keyway with the
electrode key (small black tab on the top of the electrode). Slide the plastic cover
over the electrode end and hand-tighten the cover onto the electrode. Be careful not
to cross the threads of the connector.
Slide the O-ring and ferrule down the cable to the back of the cover cap. Hand-
tighten the ferrule onto the cover cap.
-OR-
Durafet III with Vario Pin, 11 conductor connector:
Electrostatic Discharge (ESD) hazards. Observe precautions for handling
electrostatic sensitive devices.
a) Remove cover from the cable connector.
b) Make sure electrode connector and cable connector are clean and dry.
c) Align keyway of Vario Pin connector on electrode with tab inside mating connector
on cable. Press cable connector onto electrode firmly.
d) Tighten knurled busing of cable connector by hand to ensure waterproof seal.

Installation
2/04 DirectLine® DL421 Sensor Module User Manual 9
When the DL421 is specified with Table II = 3, the Remote Connector Assembly (part number
51500768-001) is supplied loose for connection of the Meredian II pH electrode cable to the
DL421 module. Table 2-4 gives the mounting procedure.
Table 2-4 Remote Mounting Procedure for Meredian II Electrodes
Step Procedure (Refer to Figure 2-4 and Figure 2-5)
1 Turning counterclockwise, remove strain relief/cover combination from the remote
connector assembly.
2 Remove the protective plastic bag from the end of the electrode cable. Be careful to
keep bare fingers away from coax cable termination.
3 Loosen and remove compression cap from strain relief fitting. Carefully push cable end
through cap and strain relief fitting so that these parts are strung back along cable
jacket.
4 Connect cable leads as follows:
Terminal 1 = Orange Reference Electrode Lead
Terminal 2 = White Temperature Compensation Lead
Terminal 3 = White Temperature Compensation Lead
Terminal 4 = Pigtail Shield Lead
Terminal 5 = NC (No Connection)
Terminal 6 = Coax Measuring Electrode Lead
Earth Ground = Yellow
5 Slide cover along cable and tighten by hand onto the remote connector assembly.
6 Slide cap along cable and tighten onto cable jacket with small wrench until cable cannot
slide within strain relief rubber bushing.
7 Remove yellow protective sleeve from opposite end of connector assembly.
8 Apply a thin film of silicon grease to the ID of electronics module’s remote mounting
cavity.
9 Plug remote connector assembly into DL421 module aligning polarity tab of module
housing and mating groove on connector.
10 Secure Electronics Module with Wall, Pipe, or DIN Rail Mounting
Mount bracket with clips facing forward, smaller clip on top and larger clip on bottom.
Wall: Use one of three through-holes to secure to wall.
Pipe: Feed hose clamp through two slots and secure to pipe.
DIN rail: Attach the appropriate DIN rail clip to the mounting bracket:
“U” DIN rail—use metal clip and shorter screw (8 mm)
“G” DIN rail—use gray clip and longer screw (10 mm)
Clip can be rotated for horizontal or vertical DIN rails.
Push electronics module onto the remote mounting bracket until it snaps into position.

Installation
10 DirectLine® DL421 Sensor Module User Manual 2/04
When the DL421 is specified with Table II = 4, the Remote Connector Assembly (part number
51500768-002) is supplied loose for connection of the HPW7000 electrode cables to the DL421
module. Table 2-5 gives the mounting procedure.
Table 2-5 Remote Mounting Procedure for HPW7000 Electrodes
Step Procedure (Refer to Figure 2-4 and Figure 2-5)
1 Turning counterclockwise, remove strain relief/cover combination from the remote
connector assembly.
2 Remove the protective plastic bag from the end of the measuring electrode cable. Be
careful to keep bare fingers away from coax cable termination.
3 Loosen and remove compression cap from strain relief fitting. Carefully push all 3 cable
ends through cap and strain relief fitting so that these parts are strung back along cable
jacket.
4 Connect cable leads as follows:
Terminal 1 = Clear Reference Electrode Coax Lead
Terminal 2 = Black Temperature Compensation Lead
Terminal 3 = White Temperature Compensation Lead
Terminal 4 = Black/White Measuring Electrode Coax Shield
Terminal 5 = Clear Measuring Electrode Coax Lead
Terminal 6 = No Connection
Earth Ground = (3) Green/White Leads from Measuring, Reference and
Temperature
5 Slide cover along cables and tighten by hand onto the remote connector assembly.
6 Slide cap along cables and tighten onto cable jackets with small wrench until cables
cannot slide within strain relief rubber bushing.
7 Remove yellow protective sleeve from opposite end of connector assembly.
8 Apply a thin film of silicon grease to the ID of electronics module’s remote mounting
cavity.
9 Plug remote connector assembly into DL421 module aligning polarity tab of module
housing and mating groove on connector.
10 Secure Electronics Module with Wall, Pipe, or DIN Rail Mounting
Mount bracket with clips facing forward, smaller clip on top and larger clip on bottom.
Wall: Use one of three through-holes to secure to wall.
Pipe: Feed hose clamp through two slots and secure to pipe.
DIN rail: Attach the appropriate DIN rail clip to the mounting bracket:
“U” DIN rail—use metal clip and shorter screw (8 mm)
“G” DIN rail—use gray clip and longer screw (10 mm)
Clip can be rotated for horizontal or vertical DIN rails.
Push electronics module onto the remote mounting bracket until it snaps into position.

Installation
2/04 DirectLine® DL421 Sensor Module User Manual 11
Figure 2-4 Remote Mounting
Cable
Connector
Housing
Electronics
Module
Electrode
Locking Screw in
Rear of Housing
Cable
Connector
Cover
Remote Wiring Cable
20 or 50 Feet
Remote Electronics
Module for
Durafet II or III Electrodes
1
2
3
4
5
6
Orange Reference Electrode Lead
White Temperature Compensation Lead
White Temperature Compensation Lead
Pigtail Shield Lead
1 Meg-ohm resistor (pre-installed by
Honeywell)
Coax Measuring Electrode Lead and
1 Meg-ohm resistor (pre-installed by
Honeywell)
Compression
Cap
Strain
Relief
Cover
Protective
Vinyl Boot
(remove)
Remote Electronics
Module for
Meredian II Electrodes
and HPW7000
Remote Wiring Cable
12 or 20 Feet for
MeredianII Electrodes,
1.5 or 36 Feet for
HPW7000
Electrode
Electronics
Module
1
2
3
6
5
4
1
2
3
4
5
6
Clear Reference Coax Lead
Black Temperature Sensor Lead
White Temperature Sensor Lead
Black/White Measuring Shield
Clear Measuring Coax Lead
No Connection
HPW7000 Electronics
Meredian II Electronics
Note: Three Green/White leads to DL421
mounting bracket screw. Mounting bracket
must be connected to earth ground.
1
2
3
6
5
4

Installation
12 DirectLine® DL421 Sensor Module User Manual 2/04
“U” Style DIN Rail “G” Style DIN Rail
Panel
PanelPanel
Terminal Connectors
View from End
Front View
View from End
Front View
Barriers, Repeater, Isolators
Hose Clamp Slot
for Pipe Mounting
Metal clip for
“U” DIN rail mounting Gray clip for
“G” DIN rail mounting
Mounting Kit
(Hose Clamp
included in kit)
Through Hole for
DIN Rail Mounting
Figure 2-5 Remote Mounting Hardware

Installation
2/04 DirectLine® DL421 Sensor Module User Manual 13
2.4 Conduit connections
The DirectLine provides a male ½” NPT thread to accommodate a customer conduit
connection. Use ½” conduit coupling (min. 38.1mm (1.5”) long) on DL conduit
connection to clear cordset connector. Conduit can not be used with field wiring
connector due to size restriction.
Do not exceed 200in-lb. torque when attaching fixed piping.
Use wrench flats provided under the ½” NPT threads to support the DirectLine
during installation.

Configuration
14 DirectLine® DL421 Sensor Module User Manual 2/04
3. Configuration
3.1 Overview
Configuration Parameters
Set Up consists of configuring the following functions:
• Buffer Group Selection – Only used with Auto Buffer Recognition calibrations.
Determines the set of standard pH buffer values to be used for Zero
(standardization) and Slope calibration by automatic buffer recognition. Each of
the available Buffer Groups is a set of 5 pH buffer standards that you can
select.
The available groups are: US (default), NIST, and EURO.
Table 3-1 Buffer Groups and the pH standard values
Buffer Group pH Buffers Display
US (default) 2 4 7 10 12 US
NIST 1.68 4.01 6.86 9.18 12.45 nISt
EURO 1 3 6 8 10 Euro
• Solution Temperature Coefficient – Typically only used in power plants for
condensate/feedwater applications. Measured pH is displayed and transmitted
to a pH value normalized to what the pH value would be if the temperature of
the process was 25 °C. Magnitude of normalization is dependent upon the
Solution Temperature coefficient, expressed in units of pH/10 °C with precision
to the hundredth decimal place.
The three available values are: 0.00 (standard setting, default), −0.16 pH/10 °C
(pure water), and −0.32 pH/10 °C (condensate/feedwater).
• Noise Suppression Frequency Selection – Selection of 50 Hz or 60 Hz.
Defaults to 60 Hz at unit reset.
• Output Configuration – The following Output Configuration functions can be
selected:
 0% Range 0 % Range values can be adjusted within a range
0.00 to 14.00 pH in 0.50 pH increments.
 100% Range 100 % Range values can be adjusted within a range
0.00 to 14.00 pH in 0.50 pH increments.
 0% Calibration Output current can be typically adjusted to within a
range of 3.80 mA to 4.40 mA.
 100% Calibration Output current can be typically adjusted to within a
range of 19.60 mA to 20.40 mA.