Wahl DST400 Digi-Stem Thermometer User Manual

: July 24, 2024
: WAHL

Table of Contents

Wahl DST400 Digi-Stem Thermometer
Product Usage Instructions
FAQ
Application and Key Features
Installation
Battery Installation Replacement
Operation
Calibration
Specifications
Service
Panel Mount Installation Instructions
Documents / Resources

Wahl DST400 Digi-Stem Thermometer

Wahl-DST400-Digi-Stem-Thermometer-PRODUCT

Specifications

Thermocouple Types: K, J, T, E, S
Battery: 3.6V Lithium Thionyl Chloride, Wahl Catalog # DSA3062
Display: LCD with error code indication

Product Usage Instructions

Installation

Read important information regarding Lithium Batteries in document #WD1053.
For remote mounting:
Mount the bracket with the Digi-Stem mounting screw towards the bottom.
Thread the cable through the slotted sections of the mounting bracket holes.
Insert the meter’s coupling nut through the top hole of the mounting bracket and secure it with the large slotted Digi-Stem mounting screw.
Re-connect the pluggable terminal strip to PCB connector J1.
Install a battery with the correct polarity as indicated on the battery holder.
Replace the cover on the Digi-Stem enclosure and secure it with four screws tightened to a force of 4 to 5 in-lbs. of torque.

Battery Installation/Replacement

If a LOW BATT warning appears, replace the battery promptly.
Loosen the four Phillips-head screws in the front cover to remove the cover.
Dispose of the old battery following local regulations.
Insert a new Wahl Catalog # DSA3062 battery with the correct polarity.
Secure the cover back with the four screws tightened to a force of 4 to 5 in-lbs. of torque.

Ventilation

The DST400 should be installed in an area with adequate air exchange to maintain specified ambient conditions.

FAQ

Q: What does “LOW BATT” on the display indicate?
A: “LOW BATT” indicates that there are approximately 4-6 weeks of battery life left. Promptly replace the battery to avoid the shutdown of the thermometer.

Q: What should I do if the display shows “- – – -“?
A: The display showing “- – – -” indicates that the battery voltage is too low for accurate measurements. Replace the battery immediately to prevent a shutdown of the thermometer.

Application and Key Features

The Wahl DST400 is designed for temperature monitoring applications where a high degree of accuracy and ease of use are desirable.

To achieve this objective the DST400 incorporates the following features:

High reliability, thin-film platinum RTD Cold Junction Compensation sensor.
High-accuracy 24-bit Delta-Sigma Analog/Digital Converter.
Error checking: Checks for open wire/sensor, under-range, over-range conditions, and low battery.
Selectable Thermocouple Type : Allows programming of meter to measure Type K, J, T, E, or S thermocouples.

Installation

Installation Caution! See important information regarding Lithium Batteries on the enclosed document #WD1053, before proceeding!
Your unit was shipped partially assembled. Installation of the battery by the end-user is necessary as transportation regulations prohibit shipping units with the battery installed.
Units with long probes or remote cables may be shipped unassembled. After installation of the battery, verify the display is operational and remove the protective film from the window.
In the event the display is not operational, check that the battery is installed properly by following the battery installation procedure, section 3 of this manual.

Meter Mounting – Fixed Probe

Fixed probes may be mounted by the threaded fitting or sanitary clamp into the process. Apply thread-sealing compound or Teflon tape to threaded fittings as required.
Units with swivel nut fittings or adjustable angle stems may be adjusted after installation for the best viewing angle.
Caution! Do not rotate Digi-Stems with adjustable angle stems more than 360 in one direction as wire breakage may occur. See section 2.5 for the adjustment procedure.
Caution! Do not use the Digi-Stem enclosure to tighten the meter. Use a wrench on the coupling nut for tightening.

Meter Mounting – Remote Probe

An optional mounting bracket is available for mounting remote meters to walls, panels, pipes, etc. The mounting bracket may be attached by the top or rear surface with user-provided mounting screws, clamps, etc.
The mounting bracket is available in 2 styles, p/n DSA3030, without ground lug and DSA3031, which includes a grounding lug for grounding of the meter when the probe shank is not grounded.

For remote mounting:

Mount the bracket with the Digi-Stem mounting screw towards the bottom (see Fig. 1).
For remote cables, thread the cable through the slotted sections of the mounting bracket holes, so the cable moves freely.
Insert the meter’s coupling nut through the top hole of the mounting bracket and secure with the large slotted Digi-Stem mounting screw.
Wire Connections – Remote probes or uninstalled fixed probes.
Loosen the four Phillips head screws in the front cover until the cover is removed.
Note: The screws are held captive by retaining washers and should not be removed completely.
Remove J1, the 2-pin pluggable terminal strip connector (see Fig. 2) from the PCB mating connector, and connect probe wires as follows.

J1 – DST400 Probe Wiring

Thermocouple Type| USA/Canada per ANSI/ASTM E230| International per IEC 584-3
---|---|---
| + Positive

+RTD/TC

| – Negative

-RTD/TC

| + Positive

+RTD/TC

| – Negative

-RTD/TC

Type S designation for Extension wire only
Re-connect the pluggable terminal strip to PCB connector J1.
Install the battery with polarity as indicated on the battery holder.
Replace the cover on the Digi-Stem enclosure and secure it with four screws tightened to a force of 4 to 5 in-lbs. of torque.

Ventilation

The DST400 should be installed in an area of adequate air exchange so that the specified ambient conditions are not exceeded.

Adjustable Angle Probe – Adjustment

Rotational adjustment, loosen the two long Phillips head screws on the ends of the bracket and rotate the bracket around the coupling nuts. Tighten screws when position is set to the desired location.
Caution! Do not rotate Digi-Stems with adjustable angles more than 360 in one direction as wire breakage may occur.
Angular adjustment, loosen the two short Phillips head screws in the center slots and pivot the bracket to the desired angle. Tighten screws.

Battery Installation Replacement

The DST400 uses a single 3.6V Lithium Thionyl Chloride battery, Wahl Catalog # DSA3062. Low battery is indicated by “LOW BATT” displayed in the lower right corner of the display (see Fig. 3).
This indicates approximately 4-6 weeks of battery life left.
Actual time will vary depending on the Display Update Rate Setting.
If the “LOW BATT” warning is ignored a “- – – -“will appear on the display indicating battery voltage is too low to make accurate measurements. This will be followed by a shutdown of the thermometer.
For installation or replacement, loosen the four phillips-head screws in the front cover until the cover is removed.
Note: The screws are held captive by retaining washers and should not be removed completely.
Remove old batteries and dispose of them per local, state, and federal regulations.
Insert new battery, Wahl Catalog # DSA3062, with polarity as indicated on the battery holder. The positive terminal should be at the top of the PCB. 3.4.
Replace the cover on the Digi-Stem enclosure and secure it with four screws tightened to a force of 4 to 5 in-lbs. of torque.

Operation

Scale Selection F/C – The temperature scale is user-selectable via jumper J8 (Fig. 2) on the Printed Circuit Board (PCB). The scale is indicated in the upper right corner of the display (Fig. 3).
Making measurements – With the battery installed and probe connected the meter automatically updates the display with the most recent measurement.
The factory default for measurement sample/display rate is 1 per 2 seconds for standard units and 1 per 4 seconds for “I” versions.
Error Codes – During normal operation, the DST400 continually performs diagnostic testing on the meter and sensor.

Errors are indicated by the following error codes:

DST400 Display Error Codes

Error Code	Description
Hi	Open sensor/wire or reading is above the specified range

Note: Open sensor indication may take up to 12 sample periods to display after the input is initially opened. It will, however, show steadily increasing readings, before displaying “Hi”.

Lo| Reading is below a specified range
– – –| Indicates Low Battery Shutdown Mode

Calibration

Background – As with all electronic Thermocouple thermometers, there are two main components to the system. The first component is the electronics, which measures the millivolt signal from the sensing element and then converts this signal to a temperature indication. The second component is the probe, also referred to as the sensor. The probe’s voltage output is a function of its temperature as defined in the ITS-90 voltage vs. temperature tables. With thermocouple sensors, the voltage measured is the sum of the “Hot Junction”, at the sensing tip and the Cold Junction” where the T/C wire is joined to the copper conductors in the meter. To get an accurate reading of the sensor tip, the signal of the “Cold Junction” must be subtracted out.
This process is sometimes referred to as “Cold Junction Compensation” or “CJC”.
The DST400 meter includes calibration of the Cold Junction Compensation circuit and must be performed anytime the meter is set to a different thermocouple type. Programming and/or calibration requires the use of the DSTCAL software package.
This package includes the USB cable, USB/DST Interface Box, and DST calibration cable. DSTCAL programming software includes the ability to set the Sample Rate, Thermocouple Type, meter mV calibration, and CJC calibration.
The DST400 uses the following methods for calibration. For more details on the calibration, see the DSTCAL software manual, WD1037.
mV Meter calibration – mV calibration on the meter is a 2-point calibration, which calibrates the DST400 voltage measuring circuits.
It requires a NIST traceable mV source with a known accuracy of 0.003mV or better at 0.000mV and ±0.012mV or better at 75.000mV.
Cold Junction Compensation (CJC) calibration – CJC calibration is a single-point calibration performed to calibrate the cold junction compensation signal with the selected thermocouple type.
This calibration MUST be performed anytime the thermocouple type of the meter is changed and must be performed using a T/C calibrator and connecting cables of the same T/C type.
The T/C calibrator should have a known accuracy of ±0.4°C or better for types K, J, T, and E or ±1.1°C or better for type S.

Specifications

Wahl-DST400-Digi-Stem-Thermometer-FIG-4

Models using an “AA” battery have a Sample/Display update rate of 4 seconds, and a 2-year battery life, 0.5 to > 3 years when set to a .25 to 10-second rate.

Service

For calibration, service, or technical support, contact our Customer Service.

Panel Mount Installation Instructions

The Panel Mount system for Wahl Digi-Stem is designed for use with panels from 1/8” to 3/8” thickness.
The system uses a square O-ring to seal around the meters H-Frame and the panel. The unit is secured by a U-bracket with 2 #8 wing nuts and lock washers.
For Panel cutout dimensions and installation reference Wahl Drawing 13615. (Shown on next).

Remove Hardware and bracket from mounting studs on the rear of the meter enclosure.
Ensure the square O-ring is installed flat against the H-frame and is not twisted.
Slide the meter from the front surface of the panel through the panel opening.
Install the U bracket over the mounting studs with the short arms facing the rear side of the panel.
Install a lock washer and wing-nut onto the studs.
Gently tighten the wing-nuts until they just start tightening. The bracket should not be deflected more than 0.020” (approximately ¾ to 1 turn after touching).

CAUTION: Excessive force may result in bending and fracturing the U bracket or damaging the mounting studs. Wahl-DST400-Digi-Stem-Thermometer-
FIG-5