Veris Technologies pH Manager - Operating Instructions - Manual (Page 61)

Pub.# OM17-MSP-pH
6-16
5. Testing that the instrument is sending the proper command to the external controller.
a) Connect the DataLogger or PC to the PC using a serial cable (you will need a null
modem and may need a gender changer). Turn on the DataLogger or PC and enter
data acquisition. The data in Hyper Terminal should look like this
$U♥♦Ç$U♥♦Ç
The impor
tant 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 DataLogger or PC. 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 DataLogger or PC
using the Controller’s cable. Go back to data acquisition in the DataLogger or PC. If
everything is working properly, the pH readings
should be something other than “-
1.00” and the message will read “1 TO START” or “INIT ERR”. Wait 10 seconds,
disconnect the external pH controller’s serial cable from the DataLogger or PC, 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 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 DataLogger or PC 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 ’$U♥♦Ç‘ from the DataLogger or PC. When the external Controller receives
this command, the reports will start with ‘7F’. At this point, the external controller waits for a
command starting with ‘$N’ or ‘$G’ from the DataLogger or PC to initialize its position and
start cycling. If the exter
nal controller never receives the ’$U♥♦Ç’ command, it stays in the
‘7E’ state and will not cycle.