WattNode Modbus FAQ
Frequently Asked Questions
- What software and hardware do you recommend to enable me to gather data from your WattNode® Modbus® and to configure its CT amps ratings?
- Why does the integer frequency register not read 600 (i.e. 10 x 60 hz.)?
- Why do the WattNode integer energy registers sometimes read negative values?
- Why do the WattNode integer energy registers show huge, sudden jumps in energy?
- What is the largest positive number that a 32-bit floating point register can represent?
- Internally, the WattNode use a 64 bit energy accumulator and then outputs that as a 32 bit IEEE-754 floating point number, which supports only six or seven decimal digits of resolution. See the last entry in the table BACnet and Modbus Energy Resolution #Output Resolution.
- Why do the floating point registers read bizzare or invalid values?
- My Modbus Master reports a CRC/checksum error or invalid response even though the WattNode’s Comm LED flashes green.
- The WattNode’s Comm LED flashes green when my Modbus Master software sends it a command message but I don’t get the expected response from the WattNode.
- How do I use a B&B 485LPRJ RS-232-to-RS-485 adapter with Modscan32 to communicate with a WattNode?
- Why does the Wattnode report code 249 (duplicate slave address) and/or 242 (message collision) even though I know the slaves on my bus all have unique addresses?
- The WattNode Modbus meter has never responded to Modbus messages. The COM LED blinks red or yellow, regardless of which address we try.
- My PLC requires a “six-digit” register address but the WattNode manual only documents “five-digit” register addresses.
- I’m writing software to communicate with the WattNode. How do I interpret the float registers?
- Why does the second register of the two registers that make up a 32-bit energy always read zero?