Pilz PNOZmulti system extension

Actual example (cascading 3 Classic bases):

Base 1 input delay: 4 ms

Base 1 Link transmission: 35 ms

Base 2 Link input delay: 0 ms

Base 2 Link transmission: 35 ms

Base 3 Link input delay: 0 ms

Base 3 output shutdown delay: 30 ms

t to ta l=four+thirty-five+0+thirty-five+0+

thirty=one hundred and four ms 

t total=4+35+0+35+0+30=104 ms

Attention: The more links there are, the more delays accumulate. When an extremely short reaction time is required, the number of cascade stages should be minimized as much as possible.

5.2 SafetyNET p RTFL Connection

The PNOZ m EF SafetyNET module can establish linear secure communication between up to 16 PNOZ multi 2 bases. The transmission delay of each module is 25 ms (the example in the manual shows a total response time of 96 ms from the 8DI4DO output of base 1 to the 8DI4DO input of base 3).

Calculation formula:

t to tal=tin_delay_B one+tproc_B one+t Safe ty NE T_tx+tin_delay_intermediate+t proc_Bx+tout_delay_lastt total=t in_delay_B1+t proc_B1+t SafetyNET_tx+t 

in_delay_intermediate+t proc_Bx+t out_delay_last

When planning, it is essential to calculate the worst-case scenario and confirm the safe distance.

Common configuration errors and troubleshooting

Fault 1: The base cannot recognize the right expansion module, and the LED displays an error code

Possible reasons:

Expansion modules exceed the number supported by the base (e.g. installing 8 modules on PNOZ m B0, error; The actual maximum is 6.

Module position error (some modules such as PNOZ m EF 2MM and 4DI4DOR have a total limit and must be placed in a specific order).

Insufficient power capacity (each module consumes backplane bus current, exceeding the rated value).

troubleshoot

Check the "System Expansion Depends on Base" table and confirm that the number of modules is compliant.

Check if the module is securely inserted into the guide rail and if the bus connector is fully inserted.

Use PNOZmulti Configurator software for hardware configuration, and compatibility and order will be automatically checked during compilation.

Fault 2: Response time exceeds safety function requirements (e.g. insufficient protection distance due to response time of safety grating)

Possible reasons:

Incorrect use of slow relay output (50 ms) instead of semiconductor output (30 ms or lower).

Added unnecessary long delays or used too many program connectors in the main program.

Not activating input filtering optimization (such as setting pulse suppression too high).

When multiple controllers are cascaded, the accumulation of transmission delay is ignored.

Optimization measures:

For time sensitive applications, PNOZ mo1p/mo3p (30 ms) is preferred over mo2p (50 ms).

Reduce timer delay in user programs or move non emergency functions to the standard output module (PNOZ m ES 14DO).

In speed monitoring, selecting the "module program" configuration method can reduce the processing overhead of the main program (but it will increase additional program connector latency, which needs to be balanced).

For Link connections, considering using SafetyNET p (unidirectional 25 ms) may be better than cascading multiple Link connections (35 ms/hop).

Fault 3: The system fails to start or frequently shuts down safely, and the fault indicates an alarm

Possible reasons:

Feedback loop wiring error (the output feedback of expansion modules such as PNOZ mo4p is not connected to the safety input of the base).

Cross short circuit detection triggered (leakage current caused by excessively long dual channel input lines or decreased insulation between lines).

Ground fault (a detection mechanism that triggers a safe shutdown due to a short circuit of an input to ground).

Troubleshooting steps:

Use the online diagnostic function of PNOZmulti Configurator to view specific fault types and channels.

Check the ground resistance of the input line and the insulation resistance between the two channels (should be greater than 1M Ω).

If it is a cross short circuit detection false alarm, the detection function can be temporarily disabled in the configuration for verification, but the final solution should be to improve cable insulation or shorten the length (Rmax=10 Ω limit).

Fault 4: Excessive delay in speed monitoring output, resulting in delayed protection action during overspeed

Reason: Frequency measurement itself requires at least one complete cycle (1/f) to confirm speed. If the speed threshold is set low and the actual frequency changes slowly, the detection time may be as long as several hundred milliseconds.

improve:

Use high-resolution encoders (such as more pulses per revolution) to shorten the measurement cycle.

Enable the 'Quick Response' mode in the configuration (if supported by the module).

Configure the speed monitoring module in the "module program" and directly link the output to the safety output to reduce the impact of the main program scanning cycle (refer to manual case 4.1.11).

Comprehensive Suggestions for System Expansion and Response Time Optimization

Pre calculate maximum response time: During the design phase, use the table provided in the manual to estimate the worst-case delay for each input-output path. Overlay the inherent delays of all external sensors and actuators (such as contactor release time, solenoid valve action time) onto the system response time to ensure compliance with standard requirements.