Description
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