Rockwell Automation T8423 Trusted TMR 120V dc Digital Input Module User Manual
Sds-8423, Trusted, Industrial control system trusted
 
SDS-8423
Trusted
TM
Industrial Control System
Trusted
TM
TMR 120V dc Digital Input Module-T8423
Issue 5 Jan 2006
FRONT PANEL
DESCRIPTION
 
The Trusted
TM
TMR 120Vdc Digital
Input module interfaces to 40 field 
input devices. A wide input voltage 
range and programmable thresholds 
allow the module to be used in 
current source and current sink 
configurations. 
Comprehensive
diagnostic tests are performed on 
each input channel, including tests for 
stuck on and stuck off failures. Fault 
tolerance is achieved through Triple 
Modular Redundancy (TMR) within 
the same module for each of the 40 
input channels. 
When a line-monitoring device is 
installed at the field switch, the 
module can detect open and shorted 
field cables. Line monitoring can be 
independently configured for each 
input channel. 
The module provides on-board 
Sequence of Events (SOE) reporting 
with a resolution of 1ms. A change of 
state triggers an SOE entry. States 
are determined by programmable 
voltage thresholds that can be 
configured on a per channel basis. 
When the field voltage and field return 
are connected to the auxiliary input 
channels of the module, thresholds 
can be specified as a ratio of the 
current field supply voltage. 
Each triplicated section of the 
module, referred to as a slice, 
conditions and measures each 
channel independently. Each slice is 
opto-isolated up to 2500V dc. Each 
slice sends its data to a safety layer 
hardware voter that presents the 
information from all three slices to the 
Trusted
TM
TMR Processor. When a
fault is detected on a slice of the 
module, 
the
Trusted
TM
TMR
Processor
will
flag
the
error,
indicating the need to replace the 
module. The Trusted
TM
TMR
Processor will continue to use the 
information provided by the remaining 
two slices until a replacement module 
is available. Replacement modules 
can be located in a standby slot next 
to the module or in a designated 
SmartSlot 
with
a
temporary
connection to the same Trusted
TM
Termination Assembly.
Modules may be placed in any I/O 
module slot in a Trusted
TM
Processor
Chassis or Expander chassis. Once 
the I/O module configuration is set, 
mechanical keying is available on all 
I/O modules to prevent inserting a 
module into an incorrect slot. 
Configuration of the module is carried 
out using the Trusted
TM
Toolset
running
on
an
Engineering
Workstation. Once configured and 
loaded into the Trusted
TM
Controller,
replacement modules are on-line 
educated by the TMR Processor. 
 
FEATURES 
40 TMR input channels per 
module 
Comprehensive diagnostics 
and self-test 
Line monitoring on a per 
channel basis 
2500V dc Opto-Isolation
On-board 1ms resolution 
Sequence of Events reporting 
Hot replaceable
Front panel status LEDs for 
each channel 
Module fault and status 
indicators 
IEC 61508, SIL 3 safety 
applications 
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