PL-TW PRECISE-LOG Thermocouple Data Logger

PL-TW PRECISE-LOG Thermocouple Data Logger
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PL-TW PRECISE-LOG Thermocouple Data Logger PL-TW PRECISE-LOG Thermocouple Data Logger PL-TW PRECISE-LOG Thermocouple Data Logger PL-TW PRECISE-LOG Thermocouple Data Logger PL-TW PRECISE-LOG Thermocouple Data Logger

The PRECISE-LOG PL-TW is an 8-channel, battery-powered, standalone and WiFi-enabled thermocouple data logger designed for industrial, laboratory, research, testing, and remote temperature-monitoring applications.

The logger provides:

  • 8 external thermocouple input channels
  • 1 onboard thermistor temperature channel
  • Built-in cold-junction compensation
  • USB and WiFi communication
  • 8 MB non-volatile flash memory
  • Direct Modbus TCP support

Each external channel can be independently configured for the required thermocouple type and input range.

The onboard thermistor measures ambient temperature and provides cold-junction compensation for accurate thermocouple measurement.

Because WiFi is built directly into the PL-TW, the logger can connect to a local wireless network without requiring Smart-Hub or another external USB Device Server. 

Multi-Channel Thermocouple Measurement

The PL-TW provides eight external thermocouple channels for multi-point temperature monitoring.

Two programmable voltage ranges are available:

  • −8 mV to +73 mV
  • −2 mV to +18 mV

Depending on the selected range, the logger supports thermocouple types:

  • B
  • C
  • E
  • J
  • K
  • N
  • R
  • S
  • T

Each channel can be independently enabled and configured through SiteView.

This allows different thermocouple types or temperature ranges to be used within the same data-logging system.

Cold-Junction Compensation

The PL-TW includes an onboard thermistor that measures ambient temperature from:

−40°C to +70°C (−40°F to +158°F)

The onboard temperature channel is used for cold-junction compensation, allowing the logger to compensate thermocouple measurements for the temperature at the logger terminals.

The onboard thermistor accuracy is:

±0.2°C from 0°C to 70°C. 

High-Resolution Data Logging

The PL-TW uses a 16-bit analog-to-digital converter with a measurement resolution of:

0.0018%

This provides high-resolution temperature measurement for laboratory, industrial, research, validation, and testing applications.

Sampling intervals are programmable from:

1 second to 12 hours. 

Standalone Operation and Long-Term Recording

The PL-TW operates independently after configuration and stores measurements in 8 MB of non-volatile flash memory.

The memory provides storage for approximately 4 million readings and retains recorded data for more than 20 years.

Logging can be configured for:

  • Immediate start
  • Delayed start
  • Field push-button activation

When memory becomes full, the logger can either:

  • Stop recording, or
  • Continue recording in FIFO mode

The built-in 3.6 V lithium battery provides up to approximately 10 years of operation at a 1-minute sampling interval in standalone mode, depending on operating conditions and configuration. 

USB and WiFi Communication

The PL-TW provides both USB and WiFi communication.

USB can be used for direct local communication with SiteView.

The built-in WiFi interface allows the logger to connect directly to a local wireless network for remote access.

Supported WiFi specifications include:

  • IEEE 802.11b/g/n
  • 2.412–2.484 GHz frequency range
  • WEP
  • WPA-PSK
  • WPA2-PSK
  • WEP64 / WEP128
  • TKIP / AES encryption

WiFi can be enabled or disabled through SiteView. 

SiteView Software

The PL-TW is supported by SiteView software.

SiteView provides tools for:

  • Configuring thermocouple channels
  • Selecting thermocouple types
  • Selecting input ranges
  • Configuring logging sessions
  • Downloading recorded data
  • Viewing real-time temperatures
  • Displaying graphs and tables
  • Configuring alarm thresholds
  • Applying custom calibration
  • Applying custom equations
  • Exporting and analyzing recorded data

SiteView can access the PL-TW through either:

  • Direct USB connection
  • WiFi / local network connection

Alarm Functions

The PL-TW provides configurable alarm functions for temperature-monitoring applications.

Each channel supports two programmable alarm thresholds.

The onboard tri-color status LED provides visual indication of:

  • Normal sampling
  • Alarm condition
  • Low battery

The LED can be disabled to reduce power consumption. 

Direct Network Access

Unlike USB-only data loggers, the PL-TW includes its own WiFi network interface.

Once connected to a local wireless network, the PL-TW can be accessed directly by supported Microedge software without requiring Smart-Hub.

Supported applications include:

  • SiteView
  • SiteView-Web
  • SiteView SDK
  • Pluto

This makes PL-TW suitable for distributed temperature-monitoring installations where loggers may be located away from the monitoring computer.

Modbus TCP Server

The PL-TW can operate directly as a Modbus TCP server.

A compatible Modbus TCP master/client can access the logger over the network and read:

  • Real-time channel readings through Input Registers
  • Logger configuration and channel information through Holding Registers

Modbus TCP support was added with PRECISE-LOG firmware version 2.06 or later. 

This allows the PL-TW to integrate directly with:

  • PLCs
  • HMIs
  • SCADA systems
  • Building-management systems
  • Industrial PCs
  • Custom Modbus software
  • Other Modbus TCP master devices

No Smart-Hub is required for PL-TW's direct Modbus TCP operation.

Rugged Industrial Design

The PL-TW is housed in a durable aluminum enclosure designed for laboratory, industrial, and field applications.

Its operating environment is:

−40°C to +70°C (−40°F to +158°F)

and:

0–95% RH, non-condensing. 

KEY FEATURES

  • 8 External Thermocouple Channels
    Provides multi-point temperature measurement using independently configurable thermocouple inputs.

  • Onboard Temperature Channel
    Built-in thermistor monitors ambient temperature and provides cold-junction compensation.

  • Multiple Thermocouple Types
    Supports B, C, E, J, K, N, R, S, and T thermocouples depending on the selected input range.

  • Two Programmable Input Ranges
    Supports −8 to +73 mV and −2 to +18 mV ranges.

  • 16-Bit Data Resolution
    Provides 0.0018% measurement resolution.

  • 8 MB Non-Volatile Flash Memory
    Stores approximately 4 million readings for long-term standalone recording.

  • 1 Second to 12 Hour Sampling
    Wide programmable sampling interval selection for both short-term testing and long-term monitoring.

  • Long Battery Life
    Up to approximately 10 years at a 1-minute sampling interval in standalone operation.

  • USB Communication
    Provides direct local communication with SiteView.

  • Built-In WiFi
    Connects directly to a wireless network without requiring an external USB Device Server.

  • Remote Network Access
    Supports SiteView, SiteView-Web, SiteView SDK, and Pluto over the network.

  • Direct Modbus TCP Support
    PL-TW can operate as a Modbus TCP server for direct integration with PLC, HMI, SCADA, and third-party systems.

  • Programmable Alarm Thresholds
    Two configurable alarm thresholds are available for each channel.

  • Flexible Logging Modes
    Supports immediate start, delayed start, field push-button activation, stop-on-full, and FIFO operation.

  • Rugged Aluminum Enclosure

TYPICAL APPLICATIONS

The PL-TW is suitable for:

  • Multi-point temperature monitoring
  • Industrial process temperature monitoring
  • Laboratory testing
  • Research
  • Product validation
  • Environmental chambers
  • Equipment testing
  • Oven and furnace monitoring
  • HVAC temperature monitoring
  • Manufacturing processes
  • Remote temperature monitoring
  • Distributed wireless temperature measurement
  • Modbus TCP temperature monitoring
  • PLC / SCADA integration
  • Long-term unattended temperature logging

DOCUMENTS



General
Product Name PRECISE-LOG Thermocouple Data Logger
Model PL-TW
External Channels 8 thermocouple channels
Internal Channel 1 onboard thermistor
Inputs
Connection Pluggable terminal block for 8 external channels
External Inputs 8 thermocouple channels
Onboard Temperature −40°C to +70°C (-40°F ~ 158°F)
Programmable Range 1 −8 mV to +73 mV
Programmable Range 2 −2 mV to +18 mV
Resolution 0.0018%
Thermistor Accuracy ±0.2°C from 0°C to 70°C
Thermocouple Accuracy ±0.1% to ±0.2% plus thermocouple accuracy
Cold-Junction Compensation Onboard thermistor
Overvoltage Protection Up to ±20 VDC
Alarms
Channel Alarm Thresholds Two programmable alarm thresholds per channel
Alarm Indicator Status LED flashes red during sampling when an alarm condition is active
On-board Memory
Flash Memory 8 MB (4MB readings) non-volatile flash memory
Data Retention More than 20 years.
Memory-Full Options Stop logging or FIFO mode
Sampling and Logging
Sampling Interval Programmable from 1 second to 12 hours
Logging Modes Stop when memory is full or continue in FIFO mode
Logging Activation Immediate start, delayed start, or field push-button activation
Communications
USB Interface Mini-USB-B
Included USB Cable USB-A to Mini-USB-B
WiFi Built-in
WiFi Standard IEEE 802.11b/g/n
Frequency 2.412–2.484 GHz
Transmit Power 11–18 dBm
Receive Sensitivity −82 to −93 dBm
Security WEP / WPA-PSK / WPA2-PSK
Encryption WEP64 / WEP128 / TKIP / AES
Encryption WEP64 / WEP128 / TKIP / AES
Communication Rate 115200 bps
WiFi Enable/Disable Configurable through SiteView
Modbus TCP Supported
Battery and Power
Internal Battery Built-in 3.6 V lithium battery
Battery Life Up to approximately 10 years at a 1-minute sampling interval in standalone mode
WiFi Power Adapter USB 5 VDC wall power adapter included
Software
Software SiteView (Sold separately)
Functions Configuration, downloading, plotting, real-time monitoring, custom calibration and custom equations
Local Communication USB
Remote Communication WiFi / local network
Computer Requirement 1.0 GHz or faster processor; 1 GB RAM or higher; 10 GB available storage or higher
Required Interface At least one available USB port
Physical Specifications
Enclosure Material Aluminum
Dimension 88 X 64.2 X 24 mm (3.46 X 2.53 X 0.95 inches)
Weight 200g
Mounting Integrated holes for wall or equipment mounting
LED Indicators
The tri-color status LED can be disabled to reduce power consumption.
Green Indication Normal sampling
Red Indication Alarm condition
Amber Indication Low battery
Operating Environment
Operating Temperature -40 ~ +70 °C (-40 °F ~ 158 °F)
Operating Humidity 0 ~ 95% RH, non-condensing
Clock Accuracy ±1 mintue per month
Approval CE, FCC

Logger Memory Capacity

Sampling Interval Enabled Channel Logging Capacity
1 minute 1 8 years
1 minute 2 4 years
1 minute 8 1 year
10 seconds 1 485 days
10 seconds 2 242 days
10 seconds 8 60 days
1 second 1 48 days
1 second 2 24 days
1 second 8 6 days

Programmable Channel Range Specifications:

Range: -8mV ~ +73mV Accuracy: ±0.1% (0.08 mV)@ 25°C + Temperature Compensation Accuracy
Thermocouple Type Temperature Range (°C) Resolution (°C) Accuracy (°C)
Type E -171 to +955 0.02 0.56
Type J -205 to +1200 0.027 0.73
Type K -270 to +1372 0.04 1.07
Type N -270 to +1300 0.045 1.21
Type T -270 to +400 0.037 1.00
Type C 0 to 2320 0.1 2.5
Type S -50 to 1768 0.04 3.85
Range: -2mV ~ +18mV Accuracy: ±0.15% (0.03 mV) @ 25°C + Temperature Compensation Accuracy
Type E -35 to 260 0.005 0.45
Type J -40 to 330 0.0062 0.56
Type K -53 to 437 0.0082 0.74
Type N -81 to 532 0.01 0.92
Type T -55 to 353 0.008 0.62
Type B 0 to 1820 0.03 3.95
Type R -50 to 1539 0.026 2.62
Type S -50 to 1704 0.03 2.9
Type C 0 to 986 0.0164 1.65

Modbus TCP support was added to the PRECISE-LOG series with firmware version 2.06. A Modbus TCP master/client can read supported Input Registers and Holding Registers directly from a PRECISE-LOG data logger over a network connection.

The following specifications list the Modbus commands and registers supported by the PL-TW data logger.

 

Input Registers:

An Input Register stores a 16-bit integer for a channel’s real-time reading. To read one or more 16-bit Input register data, use function code 4.

Register Description Type Range
0 CH0 Value Unsigned Integer 0 - 65535
1 CH1 Value Unsigned Integer 0 - 65535
2 CH2 Value Unsigned Integer 0 - 65535
3 CH3 Value Unsigned Integer 0 - 65535
4 CH4 Value Unsigned Integer 0 - 65535
5 CH5 Value Unsigned Integer 0 - 65535
6 CH6 Value Unsigned Integer 0 - 65535
7 CH7 Value Unsigned Integer 0 - 65535
8 CH8 Value Unsigned Integer 0 - 65535

Example:

To read CH2, CH3 and CH4's real-time values, a Modbus master device sends in the following command:

Data(HEX) Description Note
0001 Transaction identifier Fixed 2-byte value
0000 Protocol identifier Fixed 2-byte value
0006 Length(6 bytes are followed) 2-byte value
01 The device address 1-byte value, don't care
04 Function Code (read Input Register) 1-byte value
0002 First register's address 2-byte value
0003 The number of required registers (read 3 registers 0002 to 0004) 2-byte value

Holding Registers:

A Holding Register stores a 16-bit integer indicating a setting for the data logger. To read one or more 16-bit Holding Register data, use function code 3.

Register Description Type Range/Equation
0 Sample Interval 0: below 1 second
>=1: sample interval in second		 0 - 65535 seconds
1 Device Operating Mode 0: logging stopped
1: logger is logging data		  
10 CH0 Type 0:thermistor  
11 CH0 Enabled 0:disabled
1:enabled		 If a channel is disabled, the reading is unknown
12 CH0 Equation 0: thermistor Range: -40 to + 70 ℃ / -40 to 158 ℉
Equation for Metrics:
O = 110 * I / 65535 - 40
Equation for Imperial:
O = 198 * I / 65535 - 40
X0 CHX-1 Type 0: Wide Range -8 to + 74 mV
1: Narrow Range -2 to + 18 mV
X1 CHX-1 Enabled 0: Disabled
1: Enabled		 If a channel is disabled the reading is unknown
X2 CHX-1 Equation 0: Wide-Range Voltage Voltage Equation (mV)
O = 81 * I / 65535 - 8
1: Wide-Range TC E -171 to + 955 ℃ / -275.8 to + 1751 ℉
Temperature Equation (Metrics):
O = 1126 * I / 65535 – 171
Temperature Equation (Imperial):
O = 2026.8 * I / 65535 – 275.8
2: Wide-Range TC J -205 to + 1200 ℃ / -337 to + 2192 ℉
Temperature Equation (Metrics):
O = 1405 * I / 65535 – 205
Temperature Equation (Imperial):
O = 2529 * I / 65535 - 337
3: Wide-Range TC K -270 to + 1372 ℃ / -454 to + 2501.6 ℉
Temperature Equation (Metrics):
O = 1642 * I / 65535 -270
Temperature Equation (Imperial):
O = 2955.6 * I / 65535 – 454
4: Wide-Range TC N -270 to 1300 °C / -454 to 2372 ℉
Temperature Equation (Metrics):
O = 1570 * I / 65535 - 270
Temperature Equation (Imperial):
O = 2826 * I / 65535 - 454
5: Wide-Range TC T -270 to + 400 °C / -454 to +752 ℉
Temperature Equation (Metrics):
O = 670 * I / 65535 - 270
Temperature Equation (Imperial):
O = 1206 * I / 65535 - 454
6: Narrow-Range Voltage Voltage Equation (mV):
O = 20 * I / 65535 – 2
7: Narrow-Range TC E -35 to + 260 °C / -31 to +500 ℉
Temperature Equation (Metrics):
O = 295 * I / 65535 - 35
Temperature Equation (Imperial):
O = 531 * I / 65535 - 31
8: Narrow-Range TC J -40 to +330 °C / -40 to +626 ℉
Temperature Equation (Metrics):
O = 370 * I / 65535 -40
Temperature Equation (Imperial):
O = 666 * I / 65535 - 40
9: Narrow-Range TC K -53 to +437 °C / -63.4 to +818.6 ℉
Temperature Equation (Metrics):
O = 490 * I / 65535 - 53

Temperature Equation (Imperial):
O = 882 * I / 65535 - 63.4
10: Narrow-Range TC N -81 to +532 °C / -113.8 to +989.6 ℉
Temperature Equation (Metrics):
O = 613 * I / 65535 - 81

Temperature Equation (Imperial):
O = 1103.4 * I / 65535 - 113.8
11: Narrow-Range TC T -55 to +353 °C / -67 to +667.4 ℉
Temperature Equation (Metrics):
O = 408 * I / 65535 - 55
Temperature Equation (Imperial):
O = 734.4 * I / 65535 - 67
12: Narrow-Range TC B 0 to 1820 °C / 32 to +3308 ℉
Temperature Equation (Metrics):
O = 1820 * I / 65535
Temperature Equation (Imperial):
O = 3276 * I / 65535 + 32
13: Narrow-Range TC R -50 to +1539 °C / -58 to 2802.2 ℉
Temperature Equation (Metrics):
O = 1589 * I / 65535 - 50
Temperature Equation (Imperial):
O = 2860.2 * I / 65535 - 58
14: Narrow-Range TC S -50 to +1704 °C / -58 to 3099.2 ℉
Temperature Equation (Metrics):
O = 1754 * I / 65535 - 50
Temperature Equation (Imperial):
O = 3157.2 * I / 65535 - 58
15: Linear O = (LRH – LRL) * I / 65535 + LRL
Where:
LRH is Linear Range high value
LRL is Linear Range low value
You can get those values from SiteView
16: Wide-Range TC C 0 to 2320 °C / 32 to 4208 ℉
Temperature Equation (Metrics):
O = 2320 * I / 65535
Temperature Equation (Imperial):
O = 4176 * I / 65535 + 32
17: Narrow-Range TC C 0 to 986 °C / 32 to 1806.8 ℉
Temperature Equation (Metrics):
O = 986 * I / 65535
Temperature Equation (Imperial):
O = 1774.8 * I / 65535 + 32

Where X = 2,3,4,5,6,7,8,9
O = Output, I = Input Register Value

Example:

To read CH3's equation, a Modbus master device sends in the following command:

Data(HEX) Description Note
0001 Transaction identifier Fixed 2-byte value
0000 Protocol identifier Fixed 2-byte value
0006 Length(6 bytes are followed) 2-byte value
01 The device address 1-byte value, don't care
03 Function Code (read Holding Register) 1-byte value
002A First register's address (42 is 2A in HEX) 2-byte value
0001 The number of required registers (read 1 registers 002A) 2-byte value

Note:

  1. Modbus feature was added to firmware version 2.06 or above.

    To upgrade a data logger's firmware please refer to this link: How can I upgrade logger firmware?

  2. The age of an Input Register data is based on the Modbus request rate.

    A request of Input Register data will initiate the sampling process and the new data will be available upon the next request.

Resources:

SiteView accesses data loggers

SiteView-Web accesses data loggers

Pluto WebServer accesses data loggers

  • $688.00(USD)
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Tags: WiFi thermocouple data logger, thermocouple data logger, 8 channel thermocouple logger, multi-channel temperature logger, wireless temperature logger, Modbus TCP data logger, USB data logger, remote temperature monitoring, Type K thermocouple, Type J thermocouple, Type T thermocouple, Type E thermocouple, Type N thermocouple, Type B thermocouple, Type R thermocouple, Type S thermocouple, Type C thermocouple, cold junction compensation, PL-TW, PRECISE-LOG

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