Description
The DPM-3 WiFi, USB and RS485 communication board DPM-OPT-WXU485 allows a DPM-3 1/8 DIN digital panel meter to be interfaced to an external PC or HMI via WiFi, USB or RS485. The use of WiFi, which is standard with most computers, avoids the need for communication cables. In addition to wireless operation, high data and polling rates are a major advantage.
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-WXURS485 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 or RS485.
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-WURS485 board. Note that DPM-OPT-WURS485 and DPM-OPT-WXURS485 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.
An RJ11 connector is standard for RS485 and can be used for meter programming, for data polling as a Modbus slave at up to 115200 baud, or for operation as a Modbus master at 19200 baud to an RS485 bus with up to 31 adressable DPM-3 meters or SST series transmitters. Meters on the RS485 bus can be daisy chained using our CBL03 data cables. SST transmitters can be added using our BKBD breakout board.
Setup of WiFi, USB and RS485 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 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. DPM-OPT-WURS485 board setup and available Modbus commands are documented in our Communications Boards user manual. The USB or RS485 ports can also be used with our free Instrument Setup (IS) software to set up the host instrument and remote instruments on an attached RS485 bus.
DPM-OPT-WURS485 Meter Board with Included Cable & Antenna
WiFi Meter Operation as an RS485 Gateway