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READOUT MODES AND DATA FORMATS
CAMAC
Buffered Mode
Unbuffered mode
ECLPORT (FERA) mode
Buffered mode
Unbuffered mode
FERA COMPATIBILITY
Standard 4300B
FERA Behavior
38
This is the recommended CAMAC mode. With single word output
format, the multievent buffer will hold up to 8 full size events (512 data
words + header for each event). In double word format the buffer will
hold 4 events (1024 data words + header for each event), or up to 31
smaller events. The limit is 4095 words in the FIFO. The FIFO can
actually hold up to 8192 words, however no more events will be
accepted after the half full flag is turned on.
CAMAC readout is on an event by event basis, using F0, A0. A Q=1 is
returned if the data is valid. After the last data word for that event has
been read, the next F0, A0 always returns Q = 0. If another event is
waiting to be read the next F0, A0 will return the header word for the
next event with Q = 1, otherwise the module will continue to return Q=0.
The only difference is the behavior of the BUSY signal on the front panel
(and tested with F27, A1). Normally, the BUSY becomes true when the
common stop or common start time out is received, and remains on only
until the data is stored in the FIFO. In unbuffered mode, the BUSY is
delayed by the request delay setting (register 3), and remains true until
the data has been read from the module (the FIFO is empty again).
The behavior of the data and the BUSY signal is the same as for
CAMAC readout. This mode is NOT COMPATIBLE with 4300B FERA
ADC modules. The ECLbus must consist only of 3377 (or 3377 compat-
ible modules). Standard FERA modules may not be intermixed.
This mode IS COMPATIBLE with the original FERA modules. The 4300B
ADC modules must be installed first in the ECLbus (closer to the 4301
FERA driver). The BUSY signal now becomes the REQ line in the FERA
control bus. The request delay should be set to a value such that it
comes on after the 4300B REQ signal, but before the 4300B can finish
reading out. This mode should be used only for 4300B compatibility. If
compatibility is not required, the buffered mode should be used.
Beginning with ECO #1101, the Model 3377 time digitizer has improved
compatibility with the Model 4300B FERA ADC. This change involves
firmware only, and is compatible with all production circuit boards (rev
A&B).
With this change, the REN signal can be used as flow control for the
ECLport output in the same way as the 4300, when the 3377 is in
unbuffered mode. In addition, a new mode has been provided which
allows the use of WAK for flow control when the 3377 ECLport is oper-
ated in the fast mode. The improved compatibility is summarized below.
Conversion begins when a gate is received by the 4300B ADC module.
After the conversion is finished all modules which have data to be read
out assert the REQ line. REQ continues to be asserted until that module
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