Programmable Safety Controller SCR P
38
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6.6.1 Virtual Manual Reset and Cancel Delay (RCD) Sequence
According to section 5.2.2 of EN ISO 13849-1:2015, a "deliberate action" by the operator is required to reset a safety
function. Traditionally, this requirement is met by using a mechanical switch and associated wires connected to specified
terminals on the Safety Controller. For a monitored reset, the contacts must be open initially, then closed, and then open
again within the proper timing. If the timing is not too short or too long, it is determined to be deliberate and the reset is
performed.
BERNSTEIN has created a virtual reset solution that requires deliberate action. For example, in place of the mechanical
switch, an HMI may be used. In place of the wires, a unique Actuation Code is used for each Safety Controller on a
network. Also, each virtual reset within a Safety Controller is associated with a specific bit in a register. This bit, along with
the Actuation Code, must be written and cleared in a coordinated way. If the steps are completed with the proper sequence
and timing, it is determined to be deliberate and the reset is performed.
While the standards do not require a "deliberate action" to perform a virtual cancel delay, to avoid additional complexity,
BERNSTEIN has implemented this function in the same way as the virtual manual reset.
The user must set matching Actuation Codes in both the Safety Controller and the controlling network device (PLC, HMI,
etc.). The Actuation Code is part of the Network Settings and is not included in the configuration CRC. There is no default
Actuation Code. The user must set one up on the
Network Settings
screen. The Actuation Code can be active for up to 2
seconds for it to be effective. Different Safety Controllers on the same network should have different Actuation Codes.
The HMI/PLC programmer can choose from two different methods depending on their preferences: a feedback-based
sequence or a timed sequence. These methods are described in the following figures. The actual register location depends
upon which protocol is being used.
Note:
When a virtual manual reset or cancel delay is added in the functional view, the check list adds a
note that an actuation code must be entered under
Network Settings
.
Figure 15: Example Checklist Warning
