HF scientific MicroTOL Online Turbidimeter - Manual (Page 34)

MICRO TOL (5/10) 28
Rev. 4.8
• The same attention character “:” in ASCII or 3A Hex
• The address of the Micro TOL
• The Reading
• The Unit (NTU)
A sample communication would look like this:
(Master computer requesting a report from address #1) : 1 CRLF
(Micro TOL 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 (Catalog # 19777). This manual is also available as a free
download from our website at
www.hfscientific.com .
8.4 Flow Alarm (Catalog # 19945A)
The flow switch for the Micro TOL 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 Flow Controller (Catalog # 19778)
The flow controller limits the flow, in high-pressure systems, to safe flow limits of less
than 1 liter/minute.
8.6 Remote Panel Meter (Catalog # 19609)
The remote panel meter allows for remote indication of the NTU reading using the 4-20
mA loop. No external power is required as the meter is run off of the 4-20 mA source.