PDP11 PeripheralsHbk 1972 - Trailing-Edge

c. Output Driver Module BW403 . Is similar to the BW402 Common Power Mod·
ule except that a common ground return is provided for the open collector de·
vices of the Single Shot Driver and Flip·Flop Driver. (used with BW85 and
BW87 only)
d. Contact Sense BW731 . Provides electrically isolated, differential inputs for 16
external customer contacts or voltages. Isolation of up to 250 volts is achieved
by a miniature read relay buffer on each input point. This module provides reo
liable and trouble free digital sensing in high noise environments. Also, its dif·
ferential input characteristics are particularly suited for those applications
where the ground of the customer's excitation voltage power supply may be
different from (i.e., not directly strapped to) computer system ground.
e. Contact Interrupt BW733 - provides 16 electrically isolated, differential inputs
for external customer contacts or voltages. It is electrically and mechanically
similar to the BW731 Contact Sense Module. The BW733 is used to economically
and reliably interface asynchronous devices requiring fast service from the
processor because of priority or short duration.
9.4.5 Functional I/O Modules
a. Flip Flop Driver BM685 - Provides 16 solid state buffered driver circuits for
control of solenoid valves, relays, lamps, displays, etc. Capable of switching
control voltages of up to + 55 VDC, the BM685 will switch up to 250 ma of
field supplied power per point, when set by a logical "I." The driver includes
diode protection for inductive loads.
b. Single Shot Relay BM807 - provides 16 electrically isolated normally open mercury
wetted contact ouputs for initiating alarms, controls, and field relays.
Normally closed operation can be achieved through a module jumper change
performed in the field by the customer or at the factory on a special order
basis. The duration of the output is trimpot adjustable from 2 msec to 2 seconds.
A logical "I" energizes the relay coil for the pre· set pulse duration.
C. Single Shot Driver BM687 - Provides a solid state pulse output to activate up
to 16 field circuits such as lights, buzzers, or external control relays. Capable
of switching control voltages of up to + 55 VDC, the BM687 will switch up to
250 ma of field supplied power per point, when set by a logical "1." The driver
also provides diode protection against inductive loads.
d. Latching Relay BM803 - Provides "fail-safe" operation of 16 electrically iso·
lated mercury wetted relay outputs. Magnetically latched, the relays remain
set in the event of power failure, insuring the continuity and integrity of field
circuits. Change of state can be effected only by a logical "1" or "0." Relay
contacts are open when the relay is set by a logical "0, "and closed when set
by a logical "1." Contacts are rated at 2 amps, 250 volts, the product not to
exceed 100 va.
e. Flip Flop Relay BM805 - Provides 16 electrically isolated normally open mercury
wetted relay output contacts for buffered control of relays, contactors,
displays, lamps, etc. Normally closed operation is possible by a module jumper
change performed in the field by the customer or at the factory on a spe·
cial order basis.
f. BW734 Counter Module - Is a 10 bit asynchronous binary up counter. An output
buffer register is included which is updated after each counter increment.
When the buffer is read (under program control), the update is inhibited, pre-
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