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Once you have established communication with the unit and have a stream of information filling your
screen:
Type *@=A followed by “Enter” (or using the RS-232 communcation select menu, select A as identifier
and exit the screen) to stop the streaming mode of information. Note that the flow of information will
not stop while you are typing and you will not be able to read what you have typed. Also, the unit
does not accept a backspace or delete in the line so it must be typed correctly. If in doubt, simply hit
enter and start again. If the unit does not get exactly what it is expecting, it will ignore it. If the line
has been typed correctly, the data will stop.
You may now poll the unit by typing A followed by “Enter”. This does an instantaneous poll of unit
A and returns the values once. You may type A “Enter” as many times as you like. Alternately you
could resume streaming mode by typing *@=@ followed by “Enter”. Repeat step 1 to remove the
unit from the streaming mode.
To assign the unit a new address, type *@=New Address, e.g. *@=B. Care should be taken not to
assign an address to a unit if more than one unit is on the RS232 line as all of the addresses will be
reassigned. Instead, each should be individually attached to the RS-232 line, given an address, and
taken off. After each unit has been given a unique address, they can all be put back on the same
line and polled individually.
Tareing via RS-232 (L Series only):
Tareing (or zeroing) the flow meter provides it with a reference
point for zero flow.
This is a very simple but important step in obtaining accurate measurements
. It is
good practice to “zero” the flow meter each time it is powered up. If the flow reading varies significantly
from zero after an initial tare, give the unit a minute or so to warm up and re-zero it. If possible, it is helpful
to zero the unit near the expected operating pressure by
positively blocking
the flow downstream of the
flow meter prior to entering the Tare command. Zeroing the unit while there is
any
flow will directly affect
the accuracy by providing a false zero point. If in doubt about whether the flow is positively blocked,
remove it from the line and positively block both ports before entering the Tare command. If the unit
reads a significant negative value when removed from the line and blocked, it is a good indication that
it was given a false zero. It is better to zero the unit at atmospheric pressure and a confirmed no flow
conditions than to give it a false zero under line pressure. To send a Tare command via RS-232, enter
the following strings:
In Streaming Mode:
$$V<Enter>
In Polling Mode:
Address$$V<Enter> (e.g. B$$V<Enter>)
Sending a Set-point via RS-232 (LC Series only):
To send a set-point via RS-232, “Serial” must be
selected under the “Input” list in the control set up mode. To give controllers a set-point, or change an
existing point, simply type in a number between 0 and 65535 (2% over range), where 64000 denotes
full-scale flow rate, and hit “Enter”. The set-point column and flow rates should change accordingly. If
they do not, try hitting “Enter” a couple of times and repeating your command. The formula for performing
a linear interpolation is as follows:
Value = (Desired Set-point X 64000) / Full Scale Flow Range
For example, if your device is a 500 CCM full-scale unit and you wish to apply a set-point of 125 CCM
you would enter the following value:
16000 = (125 CCM X 64000) / Full Scale Flow Range
If the controller is in polling mode as described in
Changing from Streaming Mode to Polling Mode
, the
set-point must be preceded by the address of the controller. For example, if your controller has been
given an address of D, the set-point above would be sent by typing:
D16000 followed by “Enter”
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