Xylem TB500 ONLINE TURBIDITY ANALYZERS - Manual (Page 30)

TB500 (2/07)
Rev. 1.0 26
The TB500 will respond with:
• The same attention character “:” in ASCII or 3A Hex
• The address of the TB500
• The Reading
• The Unit (NTU)
A sample communication would look like this:
(Master computer requesting a report from address #1) : 1 CRLF
(TB500 set to address #1 Response) :001 0.0249 NTU
8.3.3 Modbus Communication
Modbus protocol communication is operational on all models. The Modbus information is
covered in a separate manual.
8.4 Flow Alarm (Model # TB500-ALR)
The flow switch for the TB500 is a factory-installed option. This option indicates a “Low
Flow” condition by switching both relays to the fail state and setting the 4-20 mA signal to
2 mA. There is also a screen indication of the low flow condition and a modbus register is
set.
8.5 Inline Flow Regulator (Model # TB500-IFR)
The inline flow regulator limits the flow, in high-pressure systems, to safe flow limits of
less than 1 liter/minute.