ICC Mirius, Installation Instructions Manual

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BACnet / Electric Water Heaters
Table 22. BACnet/Electric Water Heaters Object List
BACnet
Object Name
(Description)
BACnet
Object
Type/Inst.
BACnet
Object
Property R/W Units
Min
Value
(if W)
Max
Value
(if W)
CCB System State
(Central Control Board Control State)
Multistate Value 801 Present_Value R See
Table 22
Fault Code Multistate Value 802 Present_Value R See
Table 25
Alert Code Multistate Value 803 Present_Value R See
Table 25
1. Data is encoded into the 16 bits as major revision (upper 8 bits) and minor revision (lower 8 bits).
Central Control Board Major State Definitions
Table 23. BACnet/Electric Water Heaters Central Control Board (CCB) State
Value State
0 Off (Standby)
6 Heating
8 Fault
Energy Management System (EMS) Control
Commercial Electric water heaters with Xi controls use a single bit setting method. Within the EMS Mode-Status point one bit
command (bit 15) sets it in EMS mode, and other ends EMS mode. Once in EMS mode, another bit command (bit 0) enables heating
another disables heating.
Once in EMS mode the EMS Mode Refresh command must be periodically issued which clears a third bit (bit 14) to maintain EMS
mode, otherwise the heater will end EMS mode and resume normal operation.
Table 24. BACnet/Electric Water Heaters Energy Management System (EMS) Control
Decimal Hex Value Response
3841 0x0F01 Put into EMS Mode^ 49152 / 0xC000
0000 0x0000 EMS Disable heating^ 49152 / 0xC000
0001 0x0001 EMS Enable heating^ 49153 / 0xC001
3584 0x0E00 EMS Mode Refresh^ (must
write within 30 seconds or EMS
mode ends.) 15 seconds or
less recommended
49152 / 0xC000 or 49153 /
0xC001 depending on whether
or not heating is enabled.
Notes:
The start of a heating also depend on other factors like tank temperature dropping below Setpoint – Differential and External T’stat call
for heat if that option is enabled.
^Depending on when you poll the register, you may read bit 14 as 1 which is why a “C” (in hexadecimal form) might briefly reply with
“8”. This is due to the control setting this bit and if it not cleared periodically by the BACnet command, heating is disabled.
After disabling EMS mode with write of 3840, read back might have bits 14 and 1 possibly still set. To make sure these bits are clear,
write a 0000 to clear bit 1 and 3584 to clear bit 14.
Fault Codes and Warnings
Note:
Any Fault not listed is an internal CCB failure fault.
Table 25. BACnet/Electric Water Heaters Fault codes and Warnings
Index Range
(Decimal) Value
1 1 Okay (No Fault) (If System In Fault =0 )
1 6 Memory (If System In Fault = 1)
24 Incorrect Model