Thermo Fisher Scientific CryoExtra CE8100 Series
Operation | 47
LEVEL PERCENT COMMANDS
EVENT LOG COMMANDS
OFAF Network Setup
OFAF networking allows multiple controller to be linked
together such that all of the freezers will fill whenever any
networked Controller calls for a fill. When multiple freezers are
connected to a common supply source, it is advantageous to
fill all freezers at the same time. LN
2
transfer losses are
significantly reduced by filling all networked freezers while the
supply system is primed and cold. Using and OFAF network is
more efficient than cooling the supply system every time an
individual freezer fills. This approach is also more efficient than
employing a keep full / keep cold system. Up to 100 controller
can be connected to an OFAF network.
An OFAF network can be configured in two modes:
“Sequential” or “Simultaneous.” For both modes, when any
Controller in the network initiates a fill, the Master Controller
(OFAF ID 1) recognizes this and triggers all other Controller to
initiate fills as well.
In Sequential OFAF mode, once the Controller that initiated
the first fill has reached its High Level Setpoint, the Master will
trigger the freezer with the next sequential OFAF ID to fill until
it reaches its High Level Setpoint. The Master will then trigger
the freezer with the next sequential OFAF ID to fill and this
process will continue until all freezers in the network including
the Master have reached their High Level Setpoints.
In Simultaneous OFAF mode, when any Controller initiates a
fill and fills for at least 60 seconds, the Master will then
broadcast a signal for all freezers, including itself, to begin
filling. Each freezer will continue to fill until its High Level
Setpoint is reached.
A user would select sequential OFAF over simultaneous if
their supply system is not able to maintain the proper filling
pressure while multiple freezers filling at the same time.
Sequential OFAF allows freezers to fill one at a time with a
primed and cold supply system so that it is easier for the
system to maintain the proper filling pressure.
Figure 13. Diagram showing difference between
Sequential and Simultaneous OFAF
Network Setup
Figure 14. Diagram showing a typical OFAF
network setup
DSPN
Define 100% Point
DZER
Define 0% Point
DSPN?
100% Point Query
DZER?
0% Point Query
PCNT?
Current Percent Query
CLEVLG
Clear Event Log
LOGPER
Set Event Log Interval
DATE
Set Date
LOGPER?
Event Log Interval Query
DATE?
Date Query
TIME
Set Time
EVENT?
Last Event Query
TIME?
Time Query
EVNCT?
Number of Events Query
UNID
Set Unit ID
EVNLOG? n
Event Log [n] Query
UNID?
Unit ID Query
