GE 8723-CA-RB Railbus isolator carrier
The MOST SafetyNet System is a new additionto the MTL Open Systems product family. Sharing the
same fundamental platform as the Process Control
products, a new SafetyNet Controller, a new Earth
Line Fault Detect (ELFD) Controller Carrier and two
new SafetyNet IO Modules have been developed
and certified. The SafetyNet System uses the same
field terminals, I/O Module Carriers and Power
Supplies as the Process Control products.
Configuration and application design is carried out
using software tools specifically safety applications -
but within a common programming environment.
Certified according to IEC 61508 as a
"Programmable Electronic Safety System", MOST
SafetyNet is suitable for use in safety-related
applications up to Safety Integrity Level (SIL) 2. As
part of the family of open system components
designed by MTL for the process automation market,
it can be closely integrated with the MOST Process
Control System or used as a standalone safety
system working alongside any Process Control
solution. The system will also operate "openly" with
your choice of HMI - whatever package you use.
Emergency Shutdown, Fire & Gas and
Burner Management application requirements
are all met, with certification to IEC 61511 for
process industries and NFPA 85 for burner
management systems.
Designed for SIL 2, the SafetyNet System has
been specifically developed for safety applications,
with features that ensure safety designed in to the
product, with a simple and straightforward Safety
Manual. The net result is a product that is easy to
program, configure and use.
The modular approach provides cost effective
solutions to safety applications with limited I/O
counts per node. And since each SafetyNet node can
accommodate up to 64 I/O modules, (each of 8
channels), the requirements of safety systems with
high I/O counts are also met.
Using a 1 out of 1 with diagnostics structure
(1oo1D), a single controller, input module and
output module (together with the necessary field
terminals, carriers and power supplies and a
suitable sensor and final element) meet all the
requirements of a SIL 2 safety function.
Redundant controllers can be used to improve
availability for the SIL 2 safety function - with entirely
bumpless transfer. Further availability enhancements
can be made by the use of redundant, fault tolerant
ethernet communications and redundant power
supplies.

New additions to the family
The MOST SafetyNet System uses the same
basic structure as the MOST Process Control
System, but in addition incorporates
specifically developed components. These
are:
♦ SafetyNet Controllers (8851-LC-MT)
♦ Dedicated Controller Carriers for Earth
Leakage Fault Detection (8751-CA-NS)
♦ SafetyNet IO Modules -Analog Input
with HART (8810-HI-TX) and Discrete IO
(8811-IO-DC)
♦ Workbench software tools for use with
the SafetyNet System (8841-LC-MT)
Open communications
MTL Open System Technologies products
are just that - open. SafetyNet nodes
communicate with one another, with
standard MOST nodes, historian and asset
management packages and with HMI
packages over a fault tolerant Ethernet LAN,
running at up to 100 Mbit/s.
Peer to peer communication
SafetyNet Controllers can communicate with
one another via Ethernet using SafetyNet
P2P - which has been certified as suitable for
use in SIL 2 applications. Robust checks and
controls on access and data corruption
ensure the safety of communication and
allow safety functions for which the inputs
and outputs are widely separated to be
easily implemented - both in terms of the
software programming and in the hardware
design.