Agilent Technologies U1840A Medalist sj5000 Hardware Manual page 36

2
Introduction to the Medalist sj5000
Communications
N O T E
2-14
SMEMA Communications
A SMEMA standard is used for the machine-to-machine
electrical interface, which controls the proper sequencing of
boards. Figure 2-9 shows the wiring connection; refer to the
Electrical Drawing document for more details.
SMEMA specifies two signal lines: 'Machine Not Busy' and
'Board Available' to indicate when a machine can receive a
board and when it is ready to release a board.
Signals are communicated between machines via the 14-pin
SMEMA connector. The 'Machine Not Busy' uses pins 1 and 2
and the 'Board Available' signals uses pins 3 and 4.
The output signals to downstream machines are the 'Good
Board' signal for pins 3 and 4 and 'Bad Board' signal for pins 3
and 5.
Figure 2-9 Pins 1 to 4 of SMEMA Connector
In Figure 2-9, boards are transferred from machine A to B and
from B to C. Machine B is not busy as its pins 1 and 2 are open.
Machine A has no board available as its pins 3 and 4 are open.
• If machine A did have a board available for transfer, the
board would trip its Exit sensor and the machine would close
contact between pins 3 and 4. This would give the signal to
machine B that there is a board available.
• If machine B were processing a board, it would close the
contact between pins 1 and 2 to give the 'Machine Busy'
signal to machine A.
Board transfer only occurs when machine A has a board available
(contact closed) and machine B is not busy (contact closed).
Agilent U1840A Medalist sj5000 Hardware Manual