PILZ PNOZmulti Safety Controller Maintenance Guide

Complete guide for on-site selection and troubleshooting of PILZ PNOZmulti Classic/Mini safety controllers

In the field of industrial safety control, Pilz's PNOZmulti series configurable safety systems have become a standard choice for many equipment manufacturers and end users due to their modular design, high safety levels (PL e/SIL CL 3), and rich fieldbus interfaces. This series mainly includes two branches: PNOZmulti Classic (configurable safe compact controller) and PNOZmulti Mini (configurable safe compact controller). The two are hardware incompatible, but share the same configuration software - PNOZmulti Configurator.

When a PNOZmulti system that has been running for many years on site experiences abnormal shutdown, a certain safety output cannot be conducted, or communication interruption in the expansion module, engineers often need to quickly locate the root cause of the problem. This article will provide a complete guide for maintenance scenarios based on the core content of the system technical manual, including hardware selection, system expansion, wiring specifications, LED indicator diagnosis, error stack analysis, and system response time calculation.

PNOZmulti Classic and Mini: Core Differences and Selection Points

It is crucial to understand the structural differences between the two systems before starting troubleshooting, as their expansion modules cannot be mixed and their respective limitations directly affect the troubleshooting approach.

1.1 PNOZmulti Classic (Classic Edition)

Applicable scenarios: Starting from 4 or more security functions, high modularity and rich expansion options are required.

Basic unit models: PNOZ m0p, PNOZ m1p, PNOZ m2p (for mechanical presses), PNOZ m3p (for burners).

Scalability:

Up to 8 expansion modules (input module PNOZ mi1p/mi2p, output module PNOZ mo1p~mo5p, etc.) can be connected to the right side of the basic unit.

Up to 4 expansion modules (including analog input module PNOZ ma1p and link module PNOZ ml1p/ml2p) can be connected to the left side of the basic unit.

On the left side, one fieldbus module (such as PROFIBUS, EtherCAT, DeviceNet, etc.) can also be connected.

Through the link module PNOZ ml1p, each module can connect up to 4 distributed I/O modules PDP67 F 8DI ION (IP67), supporting up to 16 distributed modules.

Typical configuration example: one chip card+basic unit+several input/output modules+optional bus module.

1.2 PNOZmulti Mini (Compact Edition)

Applicable scenarios: Starting from 3 or more safety functions, occupying a small area, and requiring a display screen and knob for local diagnosis.

Basic unit models: PNOZ mm0p (non expandable), PNOZ mm0.1p (expandable), PNOZ mm0.2p (with integrated multi link interface).

Scalability:

PNOZ mm0p is a fixed I/O configuration (12 safety inputs+8 configurable I/O+4 semiconductor safety outputs) with no expansion slots.

PNOZ mm0.1p/mm0.2p can be connected to 1 link module/communication module and 1 fieldbus module on the left side, and PNOZ sigma series output modules (such as PNOZ s7, s10, s11, etc.) on the right side.

PNOZ mm0.2p additionally integrates a Safe Link interface (RJ45), which can directly exchange point-to-point secure data with another PNOZ multi Mini or Classic (via PNOZ ml1p).

Display and operation: Equipped with backlit LCD and knobs, it can display project names, CRC checksums, input/output status, error stacks, etc., and can perform preliminary diagnosis without the need for a computer.

Selection reminder: If PNOZ mm0p (non expandable) is used on site and there are insufficient I/O points, it cannot be solved by adding modules and must be replaced with an expandable model as a whole. If there is module damage in the Classic system, the firmware version and order number must be confirmed during replacement (such as PNOZ m1p coated and uncoated versions cannot be mixed).

System expansion and installation: the most error prone link

Many on-site failures are caused by improper physical installation or incorrect expansion configurations. The following points must be checked item by item.

2.1 Connection rules between basic units and expansion modules

Classic system:

The right expansion module (input/output) must be connected sequentially and the communication bus between modules must be connected in series using the accompanying jumper.

The extension module on the far right must have a Terminator (order number 779110) inserted into the idle interface.

The left expansion module (analog input, link, etc.) also requires jumper connections, and the leftmost module should be plugged in with terminal resistors.

Do not connect both sides simultaneously without a terminator on the only available bus interface.

Mini system (expandable model):

The left expansion module requires a black/yellow termination resistor (PNOZ mm0. xp terminator left), while the right expansion module requires a yellow termination resistor (PNOZ s terminator plug).

The type, quantity, and location of extension modules must be predefined in the hardware configuration of PNOZmulti Configurator, and any physical changes (such as adding an output module) must be re downloaded from the project.

2.2 Installation and spacing

All PNOZmulti devices must be installed vertically on a horizontal DIN rail with ventilation slots facing up/down. Other installation directions may cause overheating damage.

The protection level of the control cabinet should be at least IP54.

Maintain a minimum distance of 40mm and 20mm from other devices above and below. If the installation space is too compact, the chip card may be difficult to insert and remove. In this case, the base should be removed before replacing the chip card.

To meet EMC requirements, DIN rails must be connected to the control cabinet ground with low impedance.

2.3 Wiring taboos

Test pulse outputs: can only be used to detect input circuits (such as short circuits across emergency stop contacts), and it is strictly prohibited to drive any loads (relays, indicator lights, etc.). If the test pulse is mistakenly connected to the coil, it will immediately trigger the "FAULTRAY TEST PULSE" error and cause the safety output to shut down.

Feedback loop: When using redundant contactors, the auxiliary contacts of the contactors must be connected to the feedback input terminal (such as I14 or IM16). One of the most common reasons why the safety output cannot be restarted is due to wiring errors in the feedback loop.

Power isolation: The system power supply (A1/A2) and semiconductor output power supply (24V/0V) of the basic unit can share a 24V power supply, but if they are supplied separately, both must always be maintained. Even without using semiconductor output, the output power terminal must still be powered on.

Project loading and chip card: common fault points

The projects of PNOZmulti system are stored in chip cards. The basic unit itself does not retain the project, and will reload from the chip card every time it is powered on or reset. Therefore, chip card related malfunctions are the most common cause of downtime.

3.1 Chip card type

8 kByte (Order Number 779201/779200)

32 kByte (Order Number 779211/779212)

Large projects (exceeding 8 kByte) must use a 32 kByte card. If a low capacity card is used to store large projects, it will report "FAULTRAY PROJECT" when loading.

3.2 Project loading steps (Mini model with display screen)

Insert the chip card (pay attention to direction, do not bend).

Connect the power supply. The display screen will show the project name, CRC checksum, and creation date.

Press and hold the knob for 3-8 seconds until the loading progress is displayed. If the holding time is too short or too long, the project will not download.

After success, the RUN LED stays on and the display switches to the I/O status view.

3.3 Common Chip Card Malfunctions and Solutions

Error display meaning solution

CHIP CARD ? Clean the chip contacts without inserting a card, with a blank card or poor contact; Reinsert; Replace chip card

FAULTRA PROJECT: If the project in the card is damaged or incompatible with the firmware version, use PNOZmulti Configurator (same or higher version) to regenerate the project and download it to the card

After loading, there is no response. The RUN LED is off and the knob is not pressed correctly. After turning off the power, press and hold the knob for about 5 seconds until "Loading" is displayed

Display 'CRC: 0x0000' item as empty or no valid configuration in the card. Download the item again to the chip card via USB

3.4 Download via USB (without knob)

For Classic base units without display screens, or Mini models without knobs:

Connect the Mini USB cable (3m/5m order number 312992/312993) to the computer.

Execute 'Transfer to Device' in PNOZmulti Configurator. Note: The chip card must still be inserted as the final storage medium.

LED indicator light diagnosis: one minute quick positioning

The LEDs on the PNOZmulti base unit and expansion module are the fastest diagnostic entry point on site. Taking the six LEDs (PWR, RUN, DIAG, FAULT, I FAULT, O FAULT) shared by Classic and Mini as an example.

LED combination meaning action

Measure A1/A2 voltage (24V DC ± 20%) when the PWR power is turned off or the internal fuse is damaged; Check the external switch

RUN is turned off, FAULT flashing item is deleted or chip card is invalid, reload item

FAULT stays on, DIAG flashes, external error causes safety status: chip card not inserted, feedback loop fault, test pulse short circuit. Check chip card; Check the wiring of the feedback loop; Disconnect the load on the test pulse output

I FAULT is constantly on due to external input errors (but may not necessarily cause the safety output to be turned off), such as emergency stop with only one channel closed. Check the input signal and wiring

Output external error (safety output overload, short circuit, or feedback loop abnormality) when the O FAULT is constantly on. Measure the resistance of the output terminal to ground; Check if the load current exceeds 2A/point

RUN is constantly on, but all safety outputs are non-conductive. Internal logic conditions are not met, or the startup circuit is not reset. Check the startup button wiring and configuration of the startup type (automatic/manual)

I FAULT and O FAULT flash simultaneously. Internal hardware error. Replace the base unit

TIP: For Mini models with a display screen, rotating the knob to enter the "ERROR" menu allows you to directly see error text, such as "FEED BACK LOOP" or "PARTALLY OPERATED", without the need to remember the LED combination.

Error Stack Reading: Deep Diagnosis

When the system experiences intermittent faults or multiple alarms, the error stack is a valuable tracing tool. The basic unit can store up to 64 status and error messages internally.

5.1 Viewing Error Stack on Mini Display Screen

Rotate the knob and select the menu SHOW ERROR STACK.

Press the knob to enter. Display the latest error entry (with the highest number 1).

Each one contains: Error Class (EC), Error Information (EI), Error Number (EN), and Error Parameters (PA).

Rotate the knob to scroll through historical entries.

5.2 Common Error Messages and Countermeasures

Solution to Error Text Reason

FEED BACK LOOP feedback loop external error: contactor auxiliary contact status does not match expectations. Check if the external contactor is engaged; Whether the feedback signal is connected to the correct feedback input terminal (such as I14); Check if the feedback loop is configured but not actually wired

PARTALLY OPERATED Dual channel Safety Input: Only one channel is high level. Check if there are any broken wires or poor contacts in the wiring of the two channels; Check if the sensor itself is damaged

FAULTRA TEST PULSE Test: If the pulse output terminal is short circuited to ground or connected to a load, remove all external wiring from the T0-T3 terminals and only retain the connection to the input device; Measure the resistance to ground with a multimeter

Measure the voltage of the semiconductor output power supply (24V/0V terminal) when the voltage is lower than 19.2V; Check if the power capacity is sufficient

Measure A1/A2 voltage when the power supply voltage of the SUPERY LOW system is below 19.2V; Consider replacing the power supply with a larger capacity

If the power supply voltage of the SUPERY HIGH system is higher than 30V and the power supply voltage is reduced, it may be a fault in the stabilized power supply

The hardware configuration of CONFIGURATION is inconsistent with the project, such as inserting unconfigured extension modules or comparing the actual module type with the hardware list in PNOZmulti Configurator due to sequence errors; Reorder and download projects

Improve cabinet heat dissipation by adding fans or air conditioning when the working environment temperature exceeds 60 ℃

5.3 Reading Error Stack through Configurator

Connect the PC to the base unit via USB or Ethernet (communication module required), and click "Online" ->"Read Error Stack" in the Configurator to export a complete record containing timestamps for remote technical support analysis.

System response time calculation: verifying safety performance

When the safety function (such as emergency stop) is triggered, does the output cut-off time meet the risk analysis requirements? This requires calculating the maximum reaction time.

6.1 Calculation Formula

text

t_ReactionMax = t_InputDelayMax + t_SwitchOffDelayMax

among which

T_InputDelayMax: The maximum delay of the input module (including filtering and debounce). For the input that comes with the basic unit, the typical value is 4 ms.

T_SwitchOffDelayMax: The maximum turn off delay of the output module (including internal processing time). The semiconductor output is 30 ms, and the relay output is 50 ms.

Example: If using basic unit input+PNOZ mo1p semiconductor output, the maximum response time is 4 ms+30 ms=34 ms.

6.2 Cascade Multiple Basic Units (via Link Modules)

When two or more PNOZ multi systems are cascaded through PNOZ ml1p (Classic) or integrated Safe Link (Mini mm0.2p), the number of links needs to be multiplied in the formula:

text

t_ReactionMax = t_InputDelayMax + (n × t_BUS) + t_SwitchOffDelayMax

Among them, t_BUS=35 ms (the transmission time of data between link modules). N is the number of cascaded connection segments.

For example, three basic units are connected in series, from the input of the first unit to the output of the third unit, n = 2， The reaction time is 4 ms+(2 × 35 ms)+30 ms=104 ms.

Note: Input delay and output shutdown delay are only calculated once and will not be repeatedly accumulated.

6.3 Other factors affecting reaction time

A fixed delay time (such as a timer) configured for a certain functional block in the Configurator.

The response time of external sensors (such as light curtains).

The mechanical action time of actuators (such as contactors).

These external times must be added to the total response time of the safety circuit by the engineer themselves.

Selection and spare parts recommendations

To avoid prolonged downtime due to production stoppage or long lead times, it is recommended to establish a spare parts strategy for critical equipment.

7.1 Basic Unit Spare Parts

Model, Order Number, Applicable System

PNOZ m0p 773110 Classic entry-level

PNOZ m1p 773100 Classic Standard Extended Type

PNOZ m1p ETH 773103 Classic with Ethernet interface

PNOZ mm0p 772000 Mini non expandable type

PNOZ mm0.1p 772001 Mini Expandable Type

PNOZ mm0.2p 772002 Mini Scalable+Link Interface

7.2 Common Expansion Modules

Function Model Order Number

8 secure input PNOZ mi1p 773400

4. Safe semiconductor output PNOZ mo1p 773500

2. Safety relay output PNOZ mo2p 773520

16 standard semiconductor output PNOZ mc1p 773700

Analog input (2 channels) PNOZ ma1p 773812

Link module (for Classic) PNOZ ml1p 773540

Link module (for Mini) PNOZ mml1p 772020

7.3 Accessories and spare parts

Chip card: It is recommended to reserve at least one 32kByte card (779211) and pre write it into the currently running project.

Terminal resistance: Classic uses 779110 (universal for both sides), Mini uses 779261 (black/yellow) for the left side, and 750010 (yellow) for the right side.

Jumper: KOP-XE (774639), used for connecting modules.

Spring terminal/screw terminal: Spare one set according to on-site wiring habits.