Veris Technologies MSP EC and pH (1997-2008 floppy disk drive 1.02E) - Operating Instructions User Manual
Page 60
Veris Technologies
Pub. #OM MSP03-1
60
5. Testing that the instrument is sending the proper command to the external controller.
a) Connect the Instrument to the PC using a serial cable (you will need a null modem
and may need a gender changer). Turn on the Instrument and enter data acquisition.
The data in Hyper Terminal should look like this
$U
♥♦
Ç$U
♥♦
Ç
The important letter above is the ‘U’, but the data coming up should match this
character-for-character. The ‘U’ is the letter the pH Controller is looking for. Press
the engage (1) key on the Instrument. The data in Hyper Terminal should change to:
$N
♥♦
e$N
♥♦
e
Again, the important letter is the second letter, this time ‘N’. Pressing the (1) key will
toggle this from ‘U’ to ‘N’. Depending on settings in your controller, there may be
slight variations in the specific characters. The main issue is whether or not any
characters are transmitted.
b) Exit data acquisition. Connect the external pH Controller to the Instrument using the
Controller’s cable. Go back to data acquisition in the Instrument. If everything is
working properly, the pH readings should be something other than “-1.00” and the
message in the lower right of the instrument’s screen will read “1 TO START” or “INIT
ERR”. Wait 10 seconds, disconnect the external pH controller’s serial cable from the
back of the Instrument, and connect it to the PC’s serial port. The data coming in
from the external pH controller will be the same as in 3> above if the Instrument’s
message read “INIT ERR”, but will look something like this if the message read “1 TO
START”:
7F
-236
-284
39
7F
-236
-285
3A
If the message has changed, everything is working properly. If it has not, the
message being sent from the Instrument to the external Controller is not being
received.
To summarize, the external pH Controller sends a report starting with ‘7E’ until it receives the
command ’
$U••Ç
‘ from the Instrument. When the external Controller receives this
command, the reports will start with ‘7F’. At this point, the external controller waits for a
command starting with ‘$N’ or ‘$G’ from the Instrument to initialize its position and start
cycling. If the external controller never receives the ’
$U••Ç
’ command, it stays in the ‘7E’
state and will not cycle.