PL-VW PRECISE-LOG 8-Channel WiFi Voltage Data Logger
The PRECISE-LOG PL-VW is an 8-channel, battery-powered, standalone and WiFi-enabled DC voltage data logger designed for industrial, laboratory, research, testing, process-monitoring, and remote data acquisition applications.
The logger provides:
- 8 external DC voltage input channels
- 16-bit measurement resolution
- USB and WiFi communication
- 8 MB non-volatile flash memory
- Direct Modbus TCP support
- Long-term standalone operation
Each external channel can be independently enabled and configured for the required voltage input range.
The standard programmable input ranges are:
- 0 to 20 VDC
- 0 to 5 VDC
Because WiFi is built directly into the PL-VW, the logger can connect to a local wireless network without requiring Smart-Hub or another external USB Device Server.
Multi-Channel Voltage Measurement
The PL-VW provides eight external DC voltage channels for simultaneous monitoring of sensors, transmitters, batteries, power supplies, test equipment, and other compatible voltage-output devices.
Each channel can be independently enabled and configured through SiteView.
The standard programmable input ranges are:
- 0 to 20 VDC
- 0 to 5 VDC
The logger provides:
- 0.0018% measurement resolution
- ±0.05% FSR accuracy at 25°C
- Input impedance greater than 1 MΩ
- Overvoltage protection up to ±40 VDC
These characteristics make the PL-VW suitable for both general-purpose voltage recording and higher-accuracy laboratory or industrial measurement applications.
High-Resolution Data Logging
The PL-VW uses a 16-bit analog-to-digital converter with a measurement resolution of:
0.0018%
This provides high-resolution voltage measurement for laboratory, industrial, research, validation, and testing applications.
Standalone Operation and Long-Term Recording
The PL-VW 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-VW 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.
WiFi can be enabled or disabled through SiteView.
SiteView Software
The PL-VW is supported by SiteView software.
SiteView provides tools for:
- Configuring voltage channels
- Selecting input ranges
- Configuring logging sessions
- Downloading recorded data
- Viewing real-time voltage measurements
- Displaying graphs and tables
- Configuring alarm thresholds
- Applying custom calibration
- Applying custom equations
- Converting voltage signals into engineering units
- Exporting and analyzing recorded data
SiteView can access the PL-VW through either:
- Direct USB connection
- WiFi / local network connection
Custom equations are especially useful when the PL-VW is connected to sensors or transmitters whose voltage output represents another engineering quantity such as pressure, flow, level, position, temperature, or humidity.
Alarm Functions
The PL-VW provides configurable alarm functions for voltage-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-VW includes its own WiFi network interface.
Once connected to a local wireless network, the PL-VW can be accessed directly by supported Microedge software without requiring Smart-Hub.
Supported applications include:
- SiteView
- SiteView-Web
- SiteView SDK
- Pluto
This makes the PL-VW suitable for distributed voltage-monitoring installations where loggers may be located away from the monitoring computer.
Modbus TCP Server
The PL-VW 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 is available with PRECISE-LOG firmware version 2.06 or later.
This allows the PL-VW 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-VW's direct Modbus TCP operation.
Rugged Industrial Design
The PL-VW 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 DC Voltage Channels
Provides simultaneous multi-channel voltage measurement for sensors, transmitters, batteries, power supplies, and other compatible voltage sources.Programmable Voltage Ranges
Standard channel selections support 0–20 VDC and 0–5 VDC measurement ranges.High Measurement Accuracy
Provides ±0.05% FSR accuracy at 25°C.16-Bit Data Resolution
Provides 0.0018% measurement resolution.High Input Impedance
Greater than 1 MΩ input impedance minimizes loading of connected voltage sources.Input Protection
Voltage inputs are protected up to ±40 VDC.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 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-VW 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.Custom Engineering-Unit Conversion
SiteView custom equations can convert voltage signals into pressure, flow, level, temperature, humidity, position, and other engineering units.Rugged Aluminum Enclosure
TYPICAL APPLICATIONS
The PL-VW is suitable for:
- Multi-channel DC voltage monitoring
- Industrial sensor monitoring
- Process transmitter monitoring
- Battery voltage monitoring
- Power-supply testing
- Laboratory testing
- Research
- Product validation
- Equipment monitoring
- Environmental sensor monitoring
- Pressure sensor monitoring
- Flow and level transmitter monitoring
- Remote voltage monitoring
- Distributed wireless data acquisition
- Modbus TCP voltage monitoring
- PLC / SCADA integration
- Long-term unattended voltage logging
DOCUMENTS
| General | |
|---|---|
| Product Name | PRECISE-LOG 8-Channel WIFI Voltage Data Logger |
| Model | PL-VW |
| Inputs | |
| Connection | Pluggable terminal block for 8 external channels |
| Channels | 8 external DC voltage inputs |
| Programmable Range 1 | 0 to 20 VDC |
| Programmable Range 2 | 0 to 5 VDC |
| Resolution | 0.0018% |
| Accuracy | ±0.05% FSR @25°C |
| Input Impedance | >1 MΩ |
| Overvoltage Protection | Up to ±40 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 |
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-VW 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 |
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 |
|
| X0 | CHX-1 Type | 0: Range#0 (0 to 20 VDC) 1: Range#1 (0 to 5 VDC) 2: Range#2 (-5 to +5 VDC) |
|
| X1 | CHX-1 Enabled | 0:disabled 1:enabled |
If a channel is disabled, the reading is unknown |
| X2 | CHX-1 Equation | 0: Range#0 Voltage | Range: 0 to 20 VDC Equation O = 20 * I / 65535 |
| 1: Range#1 Voltage | Range: 0 to 5 VDC Equation: O = 5 * I / 65535 |
||
| 2: Range#2 Voltage | Range: -5 to +5 VDC Equation: O = 10 * I / 65535 – 5 |
||
| 3: 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 |
Where X = 1,2,3,4,5,6,7,8
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:
- 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?
- 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.
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