32
Serial Communication
Configuring PuTTy
1.
Download PuTTY from
putty.org
and run the installer.
2.
Open PuTTY; it will start on the Configuration screen.
3.
Click on the Terminal category. The changes we make here
will cause PuTTY to act like a normal serial terminal, such that
pressing enter will move the cursor to the next line and both
what you type and what gets returned stay on the screen:
• Check the box that says “Implicit LF in every CR.”
• Select the “Force on” radio button in the “Local echo” section.
4.
Click Connection, and then the Serial subcategory.
• Set the Speed (baud) to 19200.
• Set the Data bits to 8.
• Set the Stop bits to 1
• Ensure “None” is selected for both Parity and Flow control.
5.
Click on the Session category.
• Select the “Serial” radio button under “Connection type”.
• Check that the COM port and baud rate (Speed) are correct.
6.
Save your settings so they can be recalled again later.
✓
Note:
In what follows,
indicates an ASCII carriage return
(decimal 13, hexadecimal D). Serial commands are not case-sen-
sitive.
[unit ID]
indicates to type the unit ID, which defaults to
A
.
Polling Mode vs. Streaming Mode
In the
Streaming Mode
, the HyperTerminal® screen is updated approximately
10
–
60 times per second, depending on the amount of data on each line.
It is sometimes desirable to limit reponses to when they are requested,
which is called
Polling Mode
. This is necessary when using more than
one unit on a single RS-232 line. Each unit can be given its own unique
letter identifier or unit ID, from A through Z.
✓
Unless otherwise specified, each unit is shipped in
polling mode
with a
default Unit ID of capital A
.
Polling Mode
Polling the flow meter returns a single line of data each time you request it.
To poll your flow meter, type
A
. This does an instantaneous poll of unit A
and returns the values once. You may type
A
as many times as you like.
Poll the device:
[unit ID]
Example:
a
(polls unit A)
