AB/Rockwell Automation 1785-BCM ControlLogix PLC Programmable Logic
Controller
Revisions: Ser A Ser B Ser C
Description:
The AB 1785-BCM is a Backup Communications Module (BCM) that is
used to provide high-speed switchover of communication path using
Data Highway Plus (DH+) and Remote I/O (RIO) protocol. It is used
for redundant PLC5 processor configuration and compatible for use
with PLC5 processors such as PLC-5/15 series B, -5/20, -5/25,
-5/30, -5/40, and -5/60 processors.
Technical Specifications for 1785-BCM
Manufacturer Rockwell Automation
Module Type Backup Communications Module
Certification UL – Industrial Control Equipment, E65584 CSA – Class
1, Division 2, LR69960C
Operational Temperature 0 Deg. Celsius to 60 Deg. Celsius (32 Deg.
Fahrenheit to 140 Degree Fahrenheit)
HSSL communicates with 1.2 Megabaud
Customer Relay .25A @ 24V dc (resistive)
Keying Locations between 8 and 10 between 34 and 36
Module Location 1771 I/O Chassis (local)
Compatible processors PLC-5/15 series B, -5/20, -5/25, -5/30,
-5/40, and -5/60
Brand AB
Part Number/Catalog No. 1785-BCM
High Speed Serial Link Interface 1
DH+/RIO Interface 2
Wiring Arm 1771-WG
Bus Communcations Local PCI 2.3 Compliant
LEDs 1 Diagnosis/Status Per Channel
Max Modules Per System 4
Weight 0.3 lbs (0.1 kg)
Coating Conformal Coat
Required External Power None
Typical AC Signal Delay (Off) 29 (+/- 8) ms
Typical DC Signal Delay (Off) 30 (+/- 7) ms
Dimensions 4.5 x 12.4 x 6.3 in (115 x 317 x 160 mm)
UPC 10612598
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About 1756-L55M12
The AB 1785-BCM is a legacy communication module that is used with
the PLC5 controller platform. This module is a single-slot chassis
that is used to provide communication redundancy and switchover
capability from a primary PLC processor to a stand-by PLC5
processor. This module is able to provide high-speed Data Highway
Plus (DH+) and Remote I/O (RIO) communication backup via the
high-speed serial link (HSSL) with switchover speed up to 1.2
Megabaud.
The 1785-BCM also features an internal buffer amounting up to 4K
Words and capable of initiating switchover in different events such
as power failure, processor error including 1785-BCM partner module
fault. Additionally, switchover may also happen during manual
switchover from RUN to PROGRAM mode, REMOTE RUN to REMOTE PROGRAM
transition and REM RUN and REMOTE TEST mode changed.
The 1785-BCM is compatible for use with a variety of PLC5
processors such as PLC-5/15 series B, -5/20, -5/25, -5/30, -5/40,
and -5/60 processors. It is installed to a 1771 I/O chassis with
keying locations between 8 and 10 or between 34 and 36. It requires
use of a Wiring Arm with catalog number 1771-WG for fast
termination of communication wires to the 1785-BCM.
When using the BCM, input and output modules are not permitted to
be installed in the same chassis where the processor and the BCM is
installed. The I/O modules must be installed remotely, acting as
distributed I/O stations
