RS232 Communications Protocol & Command Set
13
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Communications Protocol
Controller Commands
Commands and responses are in the form of ASCII character strings terminated with a carriage
return <CR> ASCII character 13 (hex).
It is important to understand how the UPS circuitry switches power to the outlets in order to use
the outlet switching commands effectively. The following diagram provides a basic illustration:
The UPS provides one bank of switched outlets (Outlet Bank 1) that can be controlled independently.
These are referred to as Non-Critical Load (NCL) Outlets.
The other outlet bank (Outlet Bank 2) will be referred to as Critical Load (CL) Outlets.
Note that NCL outlets cannot be energized unless the critical load outlets are on.
NCL outlets are designated for equipment that is considered non-critical.
Power will be turned off if the battery charge falls below a set threshold (refer 2.5).
It is desirable to have the ability to switch the power to the outlets on and off to force a “hard” reboot of equipment.
Devices such as satellite receivers often “crash” and must be reset.
The following are commands made by the controller to the UPS:
AC INPUT/BATTERY
MAIN
NCL
To Non-Critical Load
(NCL)
Outlets
To Critical Load
(CL)
Outlets
Stop bit:_______________1 bit
Parity:________________None
Flow control:____________one
Baud rate:_______2400 bps
Start bit: ____________1 bit
Data length:_________8 bits
Figure 2.1 UPS Power Switching
Main Power On
Send to UPS:
MAIN_ON<CR>
If power is not switched off due to low battery conditions:
Action:
AC power is switched ON to the CL out
lets by closing the AC input relay or turn
ing on the inverter.
Response from UPS:
CL_OUTLETS_ON<CR>
NCL_OUTLETS_ON<CR> (if NCL relay is
closed)
If power is already switched off due to low battery conditions:
Action:
None
Response from UPS:
LOWBATT<CR>
Main Power Off
Send to UPS:
MAIN_OFF<CR>
Action:
All outlets are de-energized by discon-
necting the AC input relay and turning
off the Inverter.
Response from UPS:
NCL_OUTLETS_OFF<CR>
CL_OUTLETS_OFF<CR>
DB9 Pinout Diagram
5 4 3 2 1
6 7 8 9
PIN NO.
1
2
3
4
5
6
7
8
9
SIGNAL
-
TRANSMIT
RECEIVE
DTR
SIGNAL GROUND
-
RTS
-
-
DTR - Data Terminal Ready
RTS - Request To Send
