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  • WiFi interface boards are Plug & Play field installable
  • Allows DPM-3 instruments to be polled using Modbus commands
  • Can be polled every 10 msec via WiFi
  • Provides updated analog readings at up to 60 times/sec
  • Includes built-in 2.4 GHz WiFi antenna
  • Meets IEEE 802.11 b/g/n wireless standard for data rates up to 72.2 Mbits/sec
  • Includes Mini-USB port for programming or data transfer at 38400 baud

LWIFI WiFi interface board


The WiFi and USB communication board DPM-OPT-WU allows a DPM-3 1/8 DIN digital panel meter to be interfaced to an external PC or HMI via WiFi or USB. The use of WiFi, which is standard with most computers, avoids the need for communication cables.

WiFi operation complies with the IEEE 802.11 b/g/n wireless standard for data rates up to 72.2 Mbits/sec. The board can be polled every 10 msec using Modbus TCP commands as document in our Communications Boards user manual. Analog readings retrieved via WiFi can be updated 50 or 60 times per second, depending on the meter's 50 Hz or 60 Hz AC line noise rejection setting.

Cached operation is a key feature of the DPM-OPT-WU board. That board polls its host meter at the maximum rate allowed by the meter's main board, such as 60 analog readings per second, and it can in turn be polled asynchronously as a Modbus slave at a much faster rate using WiFi or USB.

An on-board 2.4 GHz antenna simplifies meter installation, but requires that the meter be installed on a benchtop or in a plastic case that is transparent to radio waves, like our BOX1 or BOX2 benchtop cases. The on-board antenna has about 10 dB less gain than the external antenna that comes with our DPM-OPT-WXU board.

A mini-USB connector is standard and can be used for meter programming or for data polling as a Modbus slave at 38400 baud in parallel with polling via WiFi. To connect to the USB port of a PC, use our cable CBL07 or another readily available A-male to Mini-B USB cable.

Setup of WiFi and USB communications uses our free Network Setup (LNS) utility. That software allows users to enter the WiFi system's SSID and password, which is then be stored on the WiFi board. It automatically discovers the board's IP address assigned by the WiFi router, the COM port used for USB communications, the meter type, and the signal conditioner type. DPM-3-OPT-WU board setup and available Modbus commands are documented in our DPM-3 Serial Communication user manual. The USB port can also be used with our free Instrument Setup to set up the host meter.

Built-In Antenna WiFi Meter Operation

Meter operation with WiFi board


WiFi Operation

WiFi application Connection to a Modbus master via a wireless router
Wireless LAN standard IEEE 802.11 b/g/n
Radio frequency 2.4 GHz license-free ISM band
Maximum data rate 72.2 Mbits/sec, MCS index 7, with 802.11 n
WiFi module ATWINC1510-MR210PB (with integral antenna)
WiFi interface 2.4 GHz printed antenna
Maximum radio range 90 m (300 ft) unobstructed outdoors

USB Operation

USB applications Our Network Setup, host meter programming, operation of host meter as a Modbus slave.
USB connector Mini-USB Type B jack
USB cable Mini-USB Type B to USB Type A (CBL07)
USB data rate 38400 baud
COM port Discovered by Network Setup (LNS) utility

Cache Operation

Data written into cache Display value only or set of 6 values (user selectable)
6 values for analog in DPMs Alarm status, display value, peak, valley, display value, display value
6 values for scale meters Alarm status, display value, peak, net weight, gross weight, display value
6 values for counters Alarm status, item 1 (display value), peak, valley, item 2, item 3
Write interval for 1 value 16.666 mecs or 20.000 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Write interval for 6 values 100 msec or 120 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Read inteval from cache Set by external Modbus Master, 10 msec minimum

Measurement Update Intervals

Analog input meter 16.666 msec or 20.000 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Totalized pulse readings Signal period or gate time from 10 msec to 199.99 sec
Frequency/rate readings Gate time + 30 msec + 1-2 signal periods

Communication Protocols

Data I/O via WiFi Modbus TCP/IP (same command set as Modbus RTU)
Data I/O via USB or RS45 Modbus RTU
Meter programming Front panel keypad or Instrument Setup (IS) software


Board dimensions 79 x 39 mm
Mounting location Middle sloft of DPM-3 digital panel meter


Operating temperature -40°C to 85°C
Relative humidity 95% from 0°C to 85°C, non-condensing
DPM-OPT-WU N/A 177.00