Safety I/O Modules Diagnostics

Description of the I/O Diagnostics

The following table lists the field diagnostics of the Safety I/O modules:

Diagnostics	Analog Input	Digital Input	Digital Output
Out of Range	yes	–	–
Broken Wire	yes	yes	–
Field Power	–	yes	yes
Overload	–	–	yes

NOTE: Short circuit of the wiring is not detected for the input modules. It is your responsibility to make sure that the modules are wired correctly.

In addition, the Quantum Safety PLC provides diagnostics of the communication between Safety CPU and Safety I/O modules, for instance a CRC. Thus, it is not only checked that the data received are the data sent but also that the data are updated. To handle disturbances, for example by EMC effects, which may temporarily corrupt your data, you can configure a maximum accepted consecutive CRC error for each module (ranging from 1 to 3). For a detailed procedure, see the chapter “Configuring I/O Modules for Safety Projects” in the Unity Pro XLS Operating Mode Manual Safety PLC Specifics .

NOTE: Unity Pro is the old name of Control Expert for versions ≤ V13.1.

Diagnostics at Power Up

At power up, the I/O modules perform an extended self-test during about 30 seconds. If these tests are unsuccessful, the modules are not considered to be healthy and do not start. The inputs and outputs are then set to 0.

If the 24 VDC external power supply is not connected to the digital input or digital output modules, the power up self-tests do not take place and the modules does not start.

Runtime Diagnostics

During runtime, the I/O modules perform self-tests. The input modules verify that they are able to read data from the sensors over the complete range. The output modules perform pulse tests on their switches with a duration lower than 1 ms.

Description of the General Over Voltage Diagnostics

Because the electronics may not work up to the theoretical maximum output voltage of the power supplies, the I/O modules must supervise the backplane power supply voltage.

The following table describes the supervision of the power supply:

The power supply of ...	Is monitored by ...
the backplane, which has a theoretical maximum output voltage of 18.5 V,	2 over voltage supervisors, that is 1 for each micro processor system. Each supervisor is able to handle a possible over voltage by opening its power switch and triggering its reset block, which manages transitions between the states of power on and power off and resets both processors when active.
the field side, which is generated by DC-to-DC converters,	2 over and under voltage supervisors, that is 1 for each micro processor system. If the 2 isolated DC-to-DC converters generating the power supply to the field side electronics experience a fault, the supervisors signal this condition to its particular processor through an isolator.
the process, which is one of the PELV type with a maximum output voltage of 60 V,	2 over and under voltage supervisors, that is 1 for each micro processor system, in the same way as they monitor the DC-to-DC converters. In case of a fault, the supervisors signal this condition to the user logic by setting a status bit in order to warn the system of possible inconsistent inputs.

DANGER

LOSS OF THE ABILITY TO PERFORM SAFETY FUNCTIONS

Use the correct process power supply, which is a PELV type with a maximum output of 60 V.

Failure to follow these instructions will result in death or serious injury.