MAN. PS 254 EN – Ind. 2 73
! The synoptic card (21700634)
The synoptic card interfaces with the following
peripheral units:
• Remote control pendant.
• Programming keyboard.
• Synoptic on the front panel.
• Display on the front panel.
• Printer.
• Memo card.
It is controlled by the sequencer card via an I²C
link.
The interface with the remote control pendant
is made by constantly checking the state of the
buttons with a line and column system. By
successively activating the different lines and
testing the columns it is determined which
buttons or switches have been activated.
The stop command BT 7 is linked directly to
the sequencer card, without passing via the I²C
bus. The emergency stop button BT 2 on the
remote control pendant is linked also to the
power on/off switch. This ensures the safety of
the users in the case of a cycle stop or an
emergency stop.
The programming keyboard is based on the
same principle. Only the key switch
"Modification authorised or not" has a direct
link.
The interface with the synoptic indicators is
made by multiplexing. The indicators are not
permanently supplied with power, but instead
by a signal (multiplexing supply) which has a
frequency of several hundred Hertz.
The contrast and brightness of the screen is
controlled by the synoptic card. The procedure
for their adjustment is given in paragraph
9.2.6.
The memo cards used with the PS 254 are
compatible with the databus I²C. The presence
of a signal "Memo card engaged", resulting
from a contact in the connector, authorises all
other connections, including the 5 V power
supply. The card is thus protected from
overloads during its insertion and its removal.
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