Racal Instruments 1256E, Руководство пользователя

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1256E User Manual
Digital Module Operation 7-2 Racal Instruments
©
2002
Synchronous Digital
Operation
When the 1260-114 modules are programmed to operate in the
synchronous mode, data will be clocked in and out of the module
by using the CLKIN line on the module’s edge connector. To
output data in the synchronous mode, one must:
A) Enable the drivers on the ports.
B) Tell the 1256 which ports of the module are to be used as
synchronous ports.
C) Load data into the memory of the 1256.
D) Arm the 1260-114 module.
E) Generate TTL-level pulses on the CLKIN pin of the module.
One data pattern is written per clock pulse.
To input data in the synchronous mode, one must:
A) Disable the drivers on the ports.
B) Tell the 1256 which ports of the module are to be used as
synchronous ports.
C) Tell the 1256 how many data bytes will be read from the
ports.
D) Arm the 1260-114 module.
E) Generate TTL-level pulses on the CLKIN pin of the module.
One data pattern is read per clock pulse.
F)
When the number of bytes specified in step (C) has been
captured, the 1260-114 automatically disarms itself.
G)
Read the number of data bytes captured from the 1256.
Mixing Synchronous
and Asynchronous
Modes of Operation
Both synchronous and asynchronous modes of operation may be
used on a 1260-114 module simultaneously. The following
restrictions apply:
A) You cannot use the asynchronous read command
DIGITAL:INPUT? to read data from a synchronous port.
B) All synchronous ports on a module must be contiguous. The
synchronous ports are always the lower numbered ports on
the module. The synchronous ports begin with port 0 and go
through port N. The asynchronous ports begin with port
(N+1), and go through port 11. For example, if the last
synchronous port is 7, then ports 0 through 7 will use the