BMXSDO0802 Output Application Wiring Examples

Introduction

You can wire the BMXSDO0802 safety digital output module to actuators to achieve SIL3 Category 4 (Cat4) / Performance Level e (PLe) compliance in different ways, depending on your requirements for high availability.

CAUTION

RISK OF UNINTENDED OPERATION

The maximum safety integrity level (SIL) is determined by the quality of actuator and the length of the proof-test interval to IEC 61508. If you are using actuators that do not meet the quality of the intended SIL standard, always wire these actuators redundantly to two channels.

Failure to follow these instructions can result in injury or equipment damage.

The following SIL3 Cat4/PLe digital output application wiring examples are described, below:

Cat4/PLe:
- a single output module channel commanding one process variable. A single actuator is employed in this design.
Cat4/PLe with high availability:
- two redundant output modules, each with a channel connected to a separate actuator, but commanding the same process variable.

CAUTION

RISK OF UNINTENDED OPERATION

When the equipment is used in a fire and gas application, or when the demand state of the output is energized:

Your proof test procedure must include a test that the cut wire detection is effective by removing the terminal block and verifying that the corresponding error bits are set.
Verify the short circuit to ground detection effectiveness, either by enabling this Pulse test to energized diagnostic function in the module's Configuration tab, or by implementing another procedure (for example, by setting the output to 1 and checking the diagnostics, and so forth.)
Avoid using lamp-like actuators, because their impedance is very low when they are switched on, which can result in a risk of detecting a false short-circuit or overload condition.

Failure to follow these instructions can result in injury or equipment damage.

Configurable Wiring Diagnostics in Control Expert

For the BMXSDO0802 safety digital output module, use its Configuration page in Control Expert to:

Enable Short circuit to 24V detection for each energized channel. This test performs the following actuator wiring diagnostics for a channel:
- Short circuit to 24 Vdc detection
- Crossed circuit detection between two output channels
Enable Open wire detection for each of eight channels, which performs the following wiring diagnostics for that channel:
- Open (or cut) wire detection (i.e. the output channel is not connected to the actuator)
- Short circuit wiring detection to the 0 Vdc ground
Enable the Pulse test to energized for each output channel. This test is performed periodically when the output is in the de-energized state, and applies a pulse (duration less than 1 ms) to the output to determine if it can transition to the energized state. If the current exceeds a threshold of 0.7 A, the output is reported as being in a short circuit condition with the 0 Vdc ground. The test period is less than 1 s.

WARNING

RISK OF UNINTENDED OPERATION

Schneider Electric recommends that you enable the available diagnostics provided in Control Expert to detect and respond to the conditions listed above. If a diagnostic test is not enabled or is not available in Control Expert, you will need to apply another safety measure to detect or exclude these conditions.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

SIL 3 Cat4/PLe - Single Digital Output Module Example

SIL 3 Cat4/PLe - High Availability Example:

Output Wiring Diagnostic Summary

The two designs provide the following wiring diagnostics:

Condition	Diagnostic Provided in Output State?
Condition	Energized	De-energized
Open (or cut) wire¹	Yes. Diagnosed each cycle.	Yes. Diagnosed each cycle.
Output in overload²	Yes. Diagnosed each cycle.	No.
Short circuit to the 0 V ground	Yes. Diagnosed each cycle.	Yes. Diagnostic period < 1 s.
Short circuit to the 24 Vdc¹	Yes. Diagnostic period < 1 s.	Yes. Diagnosed each cycle.
Crossed circuits between two channels	Yes. Diagnostic period < 1 s.	Yes. Diagnosed each cycle.
1. This diagnostic function is performed if enabled in the module Configuration tab in Control Expert. 2. After the condition is resolved, re-arm the output by de-energizing it.

WARNING

RISK OF SHORT CIRCUIT TO 0 Vdc GROUND

For the short circuit to the 0 V ground condition with the output state de-energized, it is recommended that you enable the Open wire detection option in the module’s Configuration tab. Alternatively, you will need to apply another safety measure to detect or exclude this condition.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

RISK OF SHORT CIRCUIT TO THE 24 Vdc

For the short circuit to the 24 Vdc condition with the output state either energized or de-energized, it is recommended that you enable the Short circuit to 24V detection option in the module’s Configuration tab. Alternatively, you will need to apply another safety measure to detect or exclude this condition.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

RISK OF CROSSED CIRCUITS

The module cannot detect the crossed circuits between two channels condition with the output state de-energized and the other channel de-energized. You will need to apply another safety measure to detect or exclude this condition, if it occurs when the output state changes to energized.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

RISK OF CROSSED CIRCUITS

For the crossed circuits between two channels condition with the output state de-energized and the other channel energized, it is recommended that you enable the Short circuit to 24V detection option in the module’s Configuration tab. Alternatively, you will need to apply another safety measure to detect or exclude this condition when the output state changes to energized.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

RISK OF CROSSED CIRCUITS

The module cannot detect the crossed circuits between two channels condition with the output state energized and the other channel de-energized. You will need to apply another safety measure to detect or exclude this condition.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

WARNING

RISK OF CROSSED CIRCUITS

For the crossed circuits between two channels condition with the output state energized and the other channel energized, it is recommended that you enable the Short circuit to 24V detection option in the module’s Configuration tab. Alternatively, you will need to apply another safety measure to detect or exclude this condition.

Failure to follow these instructions can result in death, serious injury, or equipment damage.