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Accelnet & Stepnet Plus Panels STO Manual 16-01338 Rev 00
Page 23 of 34 Copley Controls
8.2 Example Wiring Diagram (SIL 3 and Cat. 3 PL d STO Implementation)
8.2.1 Emergency Stop: Stopping Category 1
Figure 5 below shows a wiring example for implementing a SIL 3, Cat. 3 PL d emergency stop function using a
Accelnet & Stepnet Plus Panel s drive. The example shows a safety relay with two sets of output contacts
– one
set (K1, K2) reacts immediately to changes on the safety relay inputs and the other (K3, K4) reacts after a user-
programmable delay. A double pole, single throw E-stop switch is used to drive two independent inputs to the
safety relay. A momentary switch is wired to the safety relay reset input and is used to reset the relay at start-up
and after an E-stop event. The enable input on the drive is wired to one of the immediate response contacts.
The drive is programmed such that when this input is de-energized, the drive decelerates the motor speed in a
controlled fashion. After the user-programmed delay time, contacts K3 and K4 open and de-energize the STO
inputs to the drive. The drive STO function responds accordingly and the safe state is entered within the specified
drive STO response time. This type of implementation brings the motor speed to near zero before the STO
function is activated. It is important to note that the safe state is not entered immediately upon actuation of the
E-stop button. The safe state is entered only after the STO inputs have become de-energized and the specified
STO response time has elapsed.
8.2.2 Accelnet & Stepnet Plus Panels Configuration
[IN8] is an opto-isolated input configured for an Enable function. The [ICOM] signal for [IN8] connects to ground.
When +24 VDC is applied to [IN8] it will enable the Accelnet & Stepnet Plus Panel s if no other inputs are
configured as Enables and no Enable inputs are inactive.
If more than one input is configured as Enable, then all must be active in order to enable the drive.
The PNOZ relay uses both contacts of the delayed relay for two-channel control of the STO function, which is
necessary for SIL 3, Cat. 3 PL d.
Fig. 5