INW LEVELSCOUT INSTRUCTIONS
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Reading Via Modbus
®
RTU
Taking Measurements
Reading Registers
Read measurements using Modbus function 03 – Read Holding Registers.
Readings are located in two registers each, starting at address 62592. (PT2X register
addressing is zero based, i.e., starts at zero. If your equipment uses one based
addressing, you will need to add one to the register addresses.)
Measurement Timing
When you request a reading via Modbus, the sensor wakes up, returns the current values
in the registers, and then starts taking new readings and updating the registers. After
approximately four seconds, if no more readings have been requested, the sensor goes
back to sleep.
Because of this, the first reading you get will be old. If you are taking readings at
intervals of less than four seconds, simply ignore the first reading — all remaining
readings will be current. On the other hand, if you are taking readings at intervals of
greater than four seconds, take a reading, ignore it, wait one second, take another
reading. Record this second reading.
Data Format
The data is returned as 32-bit IEEE floating-point values, highword first, also referred to
as big-endian or float inverse.
For further information and detailed Modbus examples, see INW application note,
“
Modbus Direct Read on INW Smart Sensors
” available from our web site at http://www.
inwusa.com/appnotes.htm.
Register addresses for LevelSCOUT
Zero Based One Based
Temperature 62592 62593
Pressure
62594 62595
READING VIA DIRECT READ