Allen-Bradley 1756 Series, User Manual, Page: 14 / 136

14 Rockwell Automation Publication 1756-UM013B-EN-P - October 2019
Chapter 1 Digital Safety I/O Module Operation in a Control System
1756-IB16S Single-channel Point Operation Type
The1756-IB16S module is single-channel Point Operation Type only. The
module channels are pre-configured and fixed at single channel Point Operation
Type. The signal status of each channel is evaluated. Based on that status, safety
input data and safety input status can be off or on.
To detect discrepancy faults between the channels of a dual channel safety device,
use dual channel safety instructions the GuardLogix safety task, for example, the
Dual Channel Input Stop (DCS) instruction.
1756-OBV8S Single-channel or Dual-channel Point Operation Type
You can use the 1756-OBV8S modules only in single-channel Point Operation
Type while in bi-polar mode. Bi-polar single channel Point Operation Type
consists of a P-M pair. P is the sourcing terminal, and M is the sinking terminal.
In sourcing mode, you can configure single channel or dual-channel Point
Operation Type. In sourcing, dual-channel Point Operation Type, both channels
must always be in the same logical state.
Dual-channel Point Operation Type is typically used when both safety outputs
are controlling the same load. Rockwell Automation recommends configuring
the module for dual-channel Point Operation Type in dual-channel applications
because it decreases the dangerous undetectable failure rate (
λ
DU
) within the
module.
OUT0-P
OUT1-P
OUT4-P
OUT3-P
OUT2-P
OUT0-M
OUT1-M
OUT2-M
OUT3-M
OUT4-M
DC –
K
K
M