Table 17. Sched (Main > Configuration > Sched) - McQuay MicroTech II Operation Manual

8. BACnet BAS scheduling (priority = 9)
9. Manual (priority = 8). Note: the Manual CSM Control Mode must be set to AUTOMATIC for any of the other
scheduling methods to take command.
To view the current value of the CSM Control Mode and the priority at which it has been set, go to the System Control
screen. To view the overall effect scheduling has on the CSM Operating State, go to the System Status screen. To configure
the scheduling features, go to the Sched screen to edit the variables described in Table 17.
This section describes how to use the CSM's internal scheduling features and variables that must be set to use the BAS
scheduling method or an external time clock. For additional information on how to use the BAS scheduling function, refer
to the ED 15075 for BACnet and ED 15077 for Modbus. For information on how to connect an external time clock to UI-
13 of the CSM's onboard I/O panel, refer to the Field Wiring section of IM 781.
The CSM's optimal start feature works in conjunction with the internal weekly, holiday, and special-event scheduling
methods. When optimal start is enabled, the CSM can start the chiller system early to ensure that the loop temperature is
cold when the normal scheduled start time occurs. To configure the optimal start feature go to the Optimal Start screen to
change the values described in Table 18.
Table 17. Sched (Main > Configuration > Sched)
Name Description
Override Time This input allows you to manually set a timer that overrides the Off: Unoccupied state for the length of time specified. After it
is set the Override Time variable shows the time remaining in the override period but will only be updated if you re-enter the
Sched screen. You can reset it (up or down) at any time. If nothing else is enabling the CSM (for example, an occupied
schedule), the operating state returns to Off: Unoccupied when the timer expires. During a timed override period, the CSM's
operating state is On: Schedule. Range = 0 – 60 hour. Default = 0.00 minutes.
BAS Network This input allows you to restrict the ability of a BACnet or Modbus BAS to schedule the CSM into the occupied mode. Range
Schedule Flag = BAS Can Schedule, No BAS Scheduling Allowed. Default = BAS can Schedule
This schedule icon indicates the current occupancy status of the CSM's internal schedule. Clicking on this icon also brings up
the Schedule Editor. The Schedule Editor appears as a separate Web page, which means that your original user interface screen
is still active in the background. Range = Gray Bulb (unoccupied), Yellow Bulb (occupied). Default = Gray Bulb
Scheduling Method Interaction
When any of the above scheduling functions is calling for occupied operation, the CSM (chiller system) operates—if the
CSM Control Mode is set to Automatic on the System Control screen. Conversely, it goes into its unoccupied state only
when all of the above scheduling methods are calling for unoccupied operation. Therefore, any unused schedules should be
set for continuous unoccupied operation. An unassigned BAS schedule or a disconnected external time clock is equivalent
to an unoccupied setting for those functions.
To allow all these scheduling methods to work with each other they are each assigned a priority. If multiple scheduling
methods are setting the chiller system to occupied, the method with the lowest priority has command. When any of these
scheduling methods is not commanding the chiller system to occupied at a priority number, it is set to auto (not
unoccupied) so that higher priority methods can gain command. If none of the methods is commanding the chiller system
to occupied, the system will be unoccupied at priority 16 (the highest priority).
There are 4 scheduling methods that schedule at priority 16. Within priority 16, these methods have the following order or
importance: Timed Override, Special-event, Holiday, and Weekly. For example, if both the Special-event and Weekly
schedules were forcing the chiller system occupied, the system would actually be occupied due to the Special-event
schedule.
Setting Time and Date
The CSM uses the time and date to execute its internal scheduling functions. Refer to the "Changing the CSM's IP
Address and Date/Time" instructions in the "Getting Started" section of this document to set the CSM's date and time.
Once set, the battery-backed internal clock keeps the current time regardless of whether power is supplied to the panel. If
the battery wears out or is replaced for any reason, the time and date must be reset.
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