Pilz PNOZmulti Safety Controller Troubleshooting and Maintenance Guide

Insufficient input delay: The maximum delay for standard input is 4ms, and the minimum pulse width is 18ms. If the sensor output pulse width is less than 18ms, the system will not be able to recognize it. Please check the sensor specifications or adjust the input filtering time in the configuration.

Example: A factory's safety door switch uses dual channels, but frequent "channel inconsistency" errors occur. Upon inspection, it was found that the time difference between the actions of two contacts exceeded the configured "Simulataneity" parameter (maximum of 3 seconds). Troubleshooting after increasing the synchronization time or replacing the switch with better action synchronization.

3.3 Output circuit fault

The safety output cannot be connected or the O FAULT light is on:

Semiconductor output overload: The maximum single channel current for PNOZ m0p/m1p semiconductor output (O0~O3) is 2A (48W), and the total current is affected by temperature. If the ambient temperature is greater than 50 ° C, it is necessary to reduce the rating for use (such as reducing the coating plate to 1A/24W). When there is a short circuit, the output will immediately turn off and latch, and must be reset after power failure.

Relay output contact welding: Relay outputs (O4, O5) are used for AC loads or high current DC. Its electrical lifespan sharply decreases with the increase of switch current (see lifespan curve). For example, under AC15 0.2A, the lifespan is 1 million cycles, but if the actual load is 3A, it will decrease to about 100000 cycles. Inductive loads that frequently switch must be equipped with arc extinguishers (such as RC absorbers or varistors).

Feedback loop error: When connecting redundant outputs to external contactors, it is usually necessary to connect the auxiliary contacts of the contactors to the feedback loop (such as I14). If the feedback contact is not closed or configured incorrectly, the system will prevent the output from being connected.

Advanced fault detection: The PNOZmulti Mini base supports single channel semiconductor output "enhanced fault detection", which means that one output can carry two parallel loads while still achieving SIL CL 3. The premise is that the feedback loop has been connected and the external power short circuit has been eliminated.

3.4 Speed monitoring module (PNOZ ms1p/ms2p/ms3p/ms4p) malfunction

The speed monitoring module is used for safety speed, direction, and static monitoring. Common problems:

Encoder signal missing (Enc2 or similar): Check RJ45 connection and shielding. For TTL encoders, a 5V power supply (from the module) is required; For HTL encoders, a 24V power supply is required. If using an adapter (such as PNOZ MSI15p), confirm that the adapter is powered normally.

Improper speed threshold setting: Up to 16 speed thresholds (ms4p) can be set in the Configurator. If the actual speed is higher than the threshold but the module does not output "overspeed", check the "switch disconnection delay" configuration. Reaction time=switch off delay+10ms (f>100Hz) or 10ms+1/f (f<100Hz).

Direction monitoring error: A/B phase signals need to be connected simultaneously. If the direction error output is triggered, check the installation direction of the encoder, which can be reversed in the Configurator.

Cut off pin monitoring: When both incremental encoder and proximity switch are used simultaneously, if the encoder signal is stationary while the proximity switch is still changing, the "cut off pin" fault is triggered. This feature needs to be enabled in the configuration.

3.5 Communication and fieldbus faults

Fieldbus modules (such as PNOZ mc3p PROFIBUS, PNOZ mc8p Ethernet/IP) are unable to communicate:

Station address conflict: The PROFIBUS module uses two rotary switches to set the address (0~99), while DeviceNet uses DIP switches. Ensure that the address is unique and consistent with the main station configuration.

Terminal resistor not connected: Terminal resistors must be connected at both ends of the PROFIBUS and CANopen networks. For PROFIBUS, the module is not integrated internally and needs to be set on the connector.

Virtual input/output not configured: The data exchanged between the fieldbus module and PNOZmulti is mapped through the "Virtual Input/Output" in the Configurator. If i0~i23 is not allocated in the project, the data read and written by the main station will be empty. Attention should be paid to attribute differences when expanding to 128 points.

Diagnostic prompt: There are LEDs on the front of the fieldbus module (such as OFFLINE, ONLINE, FAULT of PROFIBUS). If ONLINE does not light up, check the bus cable and master station status.

System response time calculation and safety features

The total response time of the safety circuit (from input disconnection to output disconnection) must meet the application requirements (such as EN ISO 13849-1). The reaction time of PNOZmulti is calculated by the following formula:

t_ReactionMax = t_InputDelayMax + t_SwitchOffDelayMax

among which

The maximum input delay for the basic unit and input module is 4ms (standard input), and PNOZ mi2p is 15ms.