CLOCKS (Jul93)       furnace


clocks --- oven schedule clocks


Oven schedules consist of nodes which are composed of a GOALTIME and a GOALTEMP. The node also has a LABEL and some wait conditions which allow the schedules of various zones to be syncronized. The parameters and data for the current node of each active zone schedule are shown in the 'Oven Overview' menu. Additional details for the current node are shown in each of the 'Zone' menus. The full schedule for a particular zone is shown in the 'Zone Schedule' menu. Temperature schedules may be editted by the oven task in the 'Configuration and Status Menu'.

When the V-computer is running a temperature schedule, the clock time is advanced once per minute and the desired or scheduled temperature for each control zone is calculated. The "clock" will continue to advance minute by minute in real time unless it is "stop"ped by the pilot or the schedule encounters a wait condition. If a zone clock arrives at the endpoint of a node with a wait flag, the clock will stop advancing until the wait condition has been satisfied or until the pilot "run"s the clock. Wait flags can require any one or more of three possible conditions (T,D,W). The clock will remain stopped until all of the specified conditions have been met. Or until the pilot starts the clock manually.

There are three significant clocks associated with the oven (video doesn't count). These are the zone clocks that control the temperature schedule; the wall clock that tells you and the computers what the Mountain Standard Time is; and the minute clock which the computers use for synchronizing their tasks. These instructions assume that you are familiar with Mountain Standard Time. It is useful to know that the Sun workstations keep syncronized over ethernet and that the on-board computers are syncronized to the same clocks.

See the minutemap help file for a summary of how oven control tasks are distributed through the minute. All of the control tasks see one minute the same as the next so they don't need to know about hours or days except for the task that computes the scheduled zone temperature.


Changing the clocks on the fly is very dangerous. Do not attempt it unless you are very sure that you know what you are doing.


From the configuration and status menu, the oven pilot may set the day hour and minute of any zone clock. The pilot may also start and stop the clocks to hold or advance the temperature schedule.

To change a clock setting, move to the 'Zone' menu, move down 1 line to the 'Clock Time'. Then use 'P' to cache the parameters. Then use 'K' to cache the clock parameters. Clocks are special parameters because they are updated at the beginning of each minute. To change the CLOCKTIME, press the 'e' key and enter a new time the prompt followed by return. Both of the colons are required in the dd:hh:mm format. (ie, 0 or 6:40 are not valid entries.) To change the 'Clock Status' from 'Running' to 'Stopped' or vice versa, go to the appropriate line and use the 'e' key to toggle the parameter. When you are done changing values, use the 'W' key to write the changes to the oven or discard them (press GOTO at the option you choose). Schedule changes should be saved between 30 and 45 seconds after the minute to avoid disrupting the schedule computation.

Much of the time, you will want to make changes to the clocks of all zones simultaneously. To do this, go to the 'Global' menu under 'Configuration and Status'. The editing procedure is the same as described above.

Remember that if you change the schedule or the zone time for a clock that is stopped, you must run the clock for at least one minute to update the scheduled temperature. The corollary is that it isn't a bad idea to stop all the clocks before you start editting the schedule.





schedules, wait_states, zones, menus