29 Apr 2003
OZONECPU Operational Description for Firmware Version 2.26
Refer to the commands document for complete info.
On startup, the logger:
- initializes itself and powers up the WNDRAIN module and valve controllers
- shuts the valves if they were left open when the system was last worked on or assembled
- checks a series of setup parameters in EEPROM (these are the parameters set using the
UOK Update command, then proceeds according to the
MetMode found in EEPROM
- sends a message to the RS232 console then enters the main program loop, running
(GO mode) by default), logging MET and status data to
FLASH card, and ready to accept commands
- assuming MetMode 2 (local MET instrument) is selected, the logger immediately begins
checking the MET data
- if the wind speed is within limits and it's not raining, a minute later the inlet and
outlet valves will open and the PSI OZONE unit will be powered up
- every minute the MET data is checked, and:
- if rain is detected, shutdown (PSI turned OFF, and valves SHUT) will occur immediately
- the wind speed value is averaged for WD minutes (usually 5 minutes) and if the average is
out of limits (WMN and WMX), the system will shutdown
- otherwise, sampling continues
- once shutdown, the STAT command will show a
"waiting for rain" or "waiting for wind" message for the duration of the shutdown.
- the system will wait RD minutes to restart after the rain detection signal goes away
- after a wind shutdown, the same WD average applies, so another WD minutes must elapse
with a good average result before the system can restart
- MW can be used to disable wind speed checking entirely; then only rain detection will
stop/start the sampling.
During operation, the system status is displayed by:
Only a subset of the logger command set is available when the logger is in
GO mode (Running); an H command
shows the available commands. When the logger is in STOP mode,
a much larger set of commands is available; in particular, all the setup and FLASH card handling
commands are only available when the logger is stopped.
NOTE: STOP and GO apply to the logger system, not the PSI sampling; the system may be running in
GO mode, but OZONE sampling may be stopped if the MET situation is not appropriate for sampling.
Again, when STOPPED, an H command will show the
full command set available.
- the STAT command
- the D command (geared to another computer checking on the
- the E command (shows most recent minute MET data)
- the O command (shows the most recent PSI COM2 data message
Additional parameters in EEPROM
are used to set some limits on PSI operation and to setup for periodic ZERO checking by "switching"
an ozone scrubber in line with the airflow. These parameters are set under the
UOK Update command, as operating parameters OP0 thru OP9 -
refer to the OP settings. OP1 and OP2 set the amount of time that
the PSI will remain OFF after an error even if the MET data indicates it's OK to sample. OP0 sets the
maximum allowable PSI CPU temperature (as indicated in the COM2 data output). OP3 and OP4 set the lower
and upper limits of the valve position (normal value is 42, also indicated in the COM2 data output).
Parameter OP5 sets the number of hours between ZERO checks; setting it to 0 disables ZERO checking. This
time interval is based on actual sample time, not calendar time. That is, if OP5 is set for 24, then 24
hours of PSI sampling time must elapse between ZERO checks. OP6 sets the duration of the ZERO check in
minutes, for example 15 minutes. ZERO checking only happens when it's OK to sample per the MET
checking; i.e. the PSI must currently be running for the ZERO check to commence. Once the ZERO check
starts, the main inlet will remain closed and the scrubber switched in for the OP6 duration,
UNLESS the MET check requires a shutdown due to rain or wind. In this case, the ZERO check
may abort part way through. It will NOT be restarted when it is OK to sample again. Normal
sampling will simply resume and another OP5 hours interval will commence. Finally, OP9 is ALWAYS
set to 60 for normal operation of the ZERO checking. OP9 is the minutes multiplier for OP5, since the
timing is internally handled in minutes. (This is useful as outlined below...)
Note that during all operation, the STAT command will
indicate, among other things, GO/STOPPED status of the logger, OZONE sampling if the PSI is running,
the time left (in minutes) until the next ZERO check, or, if ZERO checking is currently happening,
the time left in the ZERO check.
IMPORTANT NOTE about changing setup parameters via the UOK
Otherwise, some settings will continue to run at their old values until reloaded during normal
For example, the logger only checks for ZERO checking enabled on powerup; if you enable or
disable it by STOP_muck_about_in_UOK_GO commands, the ZERO check state will NOT be changed
until power is cycled. If you change ZERO check interval or duration, these values will not
be updated until the original settings have run through one time.
this warning does NOT apply to STOP and GO for setting the CLOCK, manipulating the FLASH card,
testing the MET module, or using XMODE to dump FLASH data.
- After STOPping the logger and making changes to EEPROM setup parameters, it is always
a good idea to cycle logger power to cause a clean restart under the new parameter settings.
ZERO CHECK TESTING
In order to facilitate testing of the system including ZERO checking, OP9 may be set to something
other than 60 minutes. Simplest is to set it to 1 so that the OP5 setting now equals minutes for
testing. Thus, if OP5 = 24 and OP6 = 15 and OP9 = 1, after every 24 minutes of sampling, the ZERO
check solenoid will energize, the inlet will close and for the next 15 minutes, incoming air will
be scrubbed. After 15 minutes, the inlet will open, the ZERO check solenoid valve will de-energize,
and a new 24 minute sampling period will begin.
If the logger starts up with OP9 set to something other than 60, the
STAT command will display a WARNING!
message about this, AND the logger will start a 24 calendar hour timeout on
ZERO checking that WILL disable ZERO checking for the duration of the logger operation.
*** DON'T FORGET TO PUT OP5, OP6, and OP9 BACK TO NORMAL AFTER TESTING! ***
- Use the TM command to test the WNDRAIN module
while attached to the logger.
- DON'T CHANGE the RI value under UOK - leave it at 60!!!
- When changing parameters, if you get confused, just ABORT and the EEPROM values will
- Use the SETUP command anytime to see the
current operating parameters.