Description
The DPM-OPT-WXU WiFi and USB communication board 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-WXU board. That board polls its host meter at the maximum rate allowed by the meter's main board, and it can in turn be polled asynchronously as a Modbus slave at a much faster rate using WiFi, USB.
An external 2.4 GHz antenna with an antenna gain of 5 dBi is connected to the meter by a 30" (76 cm) low-loss RG174 cable. Use of an external antenna allows the meter to be installed in a metal cabinet and the top of the cabinet to serve as the ground plane for the antenna. Use of an external antenna increases signal strength by about 10 dB compared to that of the internal antenna used in our DPM-OPT-WU WiFi board. Note thal DPM-OPT-WU and DPM-OPT-WU equipped meters can be mixed in the same system.
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 Laurel Network Setup (LNS) utility. That software allows users to enter the WiFi system's SSID and password, which is then be stored in 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. LWIFI board setup and available Modbus commands are documented in our DPM-3 Serial Communication Manual Communications Boards user manual. The USB port can also be used with our free Instrument Setup (IS) software to set up the host instrument.
WiFi meter external antenna Operation