Automation Canada Machine Safety Issue May 2021 - 13

Logic Documentation
Documentation is needed to describe the logic of each module as
required under section 8.6. This is a must-have when there are multiple
users, over multiple periods, that need to access the same information,
or that need to jump in and do different tasks. Samos® Plan, for
example, provides documentation both inside and outside the
soſtware.
Inside the soſtware, the help file provides a detailed explanation of
each module, what its maximum capabilities are, and the general sense
of the programming, what each parameter does, and what each input &
output does. In addition, a timing diagram, allows you to view how the
logic relates to one another.
We also implement a logic simulator. It is necessary to have simulation
under IEC 62061 Section 8.2. This facilitates logic testing, fault
simulation, and code testing. All are tools that are essential when
developing a safety application.
Simulation Tools
Simulation can be done in real-time, at a slow speed, or even in fixed
time steps for a detailed analysis. With superior
tools
to
test,
understand, and troubleshoot your logic, safety compliance becomes
much simpler.
Another tool, the Logic Analyzer, allows you to track and generate
timing diagrams for your safety project. You can choose which signals
you want: inputs, outputs, and intermediate values, in the logic. They
can be charted easily and quickly to visualize causality. This can be used
for troubleshooting, but also documentation so that your customers
and end-users can see how things are supposed to interact.
This can be done in simulation mode when you are at the early stages
of the design cycle. However, it can also be used as a signal analyzer, or
a " soſt oscilloscope " when you are connected to the controller. This
removes the need for additional tools to troubleshoot the device when
it is in the field. Paired with remote diagnostic, remote signal analysis is
possible. Validation is also easy because signals can be recorded
on-site. In addition, long-term data can be stored for easy
CANADIAN AUTOMATION
troubleshooting.
Finally, a force mode function, much like a simulation, allows for the
control of the values of inputs and overrides them so that you can
simulate things that are happening in your machine and recreate
situations that might be otherwise difficult to recreate.
Force mode is done while connected to the controller and used to
override the inputs. It is in the soſtware, but the outputs are very real; the
controller will drive machinery based on the inputs provided. The
inputs can be forced, high and low, to test machines in scenarios that
may otherwise be difficult to realize, such as simulating sensors that are
missing. It can also help to avoid situations where you might decide to
bypass the safety sensor by putting in a jumper wire.
Being built-in to a safety soſtware, the force mode itself needs to
comply with certain safety principles including limiting the time that you
can remain in this mode. This prevents you from having a permanent
override to a safety function and is much safer than using a jumper wire,
which can easily be forgotten.
Documentation & Reporting Tools
A huge part of designing a safety application is of course
documentation and reporting. The regulations demand not only that
safety checks have been done, but there needs to be proof of those
checks and tests. Having tools for report generation makes life much
easier, and it is a must for any safety soſtware that you are considering.
A one-click report generation tool, such as the one on the Samos®
Plan 6, allows you to generate a report that includes all of the necessary
information with one click. This report gives you information on the
logic, the soſtware version, hardware versions, serial numbers, and
wiring. If there is a fault history, you have that documented as well.
Section 8.1 and 8.12 require that there should be the management of
soſtware versioning during testing. This report provides a CRC Number
or checksum. Any changes you make to the soſtware will change the
CRC Number, allowing you to quickly and easily identify which version
you are looking at.
VOLUME 3, ISSUE 3
13
Automation Canada Machine Safety Issue May 2021

Table of Contents for the Digital Edition of Automation Canada Machine Safety Issue May 2021
