Communications Interface; System Response Time - Hoffer Flow Controls HIT-2A User Manual

3-1-6

Communications Interface

The communication is provided through a RS232C interface to
the Microcontroller. The external terminal device provides the
power for the RS232 interface. The Communications Interface is
used to configure and trouble-shoot the device.
3-1-7 Clearing Total
The Total amount stored in HIT-2A memory can be cleared from
the front panel program menu, by external momentary switch
wired to the reset input, or by external magnet. The magnet has to
be brought close to top of the front panel.
3-2

System Response Time

The displayed Rate and Total are updated every two (2) seconds. The
analog output response time to reach steady state due to a change in the
flow rate is also approximately two (2) seconds. When flow stops, the
time for the analog output to return to 4 mA will be between 3 and 12
seconds, depending on the Maximum Sample Time (MST) setting.
MST is adjusted using the NB= (DATA) command, where NB is a
value between 1 and 80. The default MST setting is NB= 1. Adjusting
the MST is only recommended for low flow applications where the
minimum input frequency is below 1 Hz.
Theory of Operation 9
HP-306