HP 5501A Operating And Service Manual page 129

FORMULA: X
= (D
-
160) (K) (C)
Where: X is compensated inches or millimeters of displacement data,
D is uncompensated counts from the 10760A Counter card,
K is the inch or millimeter conversion factor (6.23023 x 106 for inches and
1.58248 x 10-4 for millimetres),
C is the velocity-of-light compensation factor from the manual or automatic
compensator.
NOTE
If the system is operated in the "X10" extended resolution mode, the
formula must be changed to subtract 16 counts instead of the 160
counts specified above.
4.9 COMPUTER-BASED SYSTEM PROGRAMMING
Several different configurations of laser transducer systems can be controlled by a digital com-
puter. The following discussion refers specifically to a system using the 10740A Coupler and
the 10746A Binary Interface.
The binary interface module allows a digital computer to control the laser transducer system
if the computer has its own input/output circuits or has other means for accomplishing the
following:
a.
It
must send a "command" signal to the binary interface module to start each functional
operation.
b. I t must accept a "flag" signal from the binary interface module. The "flag" signal
signifies completion of a function by the binary interface module.
c.
It
must have a set of data lines to allow passage of binary data to and from the binary
interface module.
The data lines between the binary interface module and the computer can be separated into
input and output lines, or can use common input/output lines. In either case, only one oper-
ation can take place at a time. Data words can consist of either 8 or 16 bits; 12-bit computers
must use &bit words and pack them, if desired, by software means.
The general sequence for a computer-controlled operation is a s follows:
a. The computer outputs an instruction to a register on the computer output interface
circuit assembly.
b. The computer sends a "command" signal to the 10746A Binary Interface. The "com-
mand" signal causes the 10746A to accept the instruction and perform the associated
function.
c. The 10746A returns a "flag" signal to the computer to indicate acceptance of the
instruction.
d. The computer can now proceed to other program steps. For example, the steps re-
quired to input data from i ts interface register if the original instruction specified a
data transfer from the 10746A to the computer.
If the "command" signal is removed by the computer, the "flag" signal from the 10746A
will be immediately reset. The signal therefore, should not be removed until all flag-dependent
transfers have been completed.