PILZ PNOZ m B0 configurable safety control system basic unit

PILZ PNOZ m B0 Safety Controller On site Troubleshooting and Debugging Guide

In the industrial automation safety circuit, Pilz's PNOZmulti 2 series configurable safety system is widely used in emergency stop, safety door, two hand button and other scenarios due to its high flexibility and high safety level. As the fundamental unit of this series, PNOZ m B0 undertakes the core tasks of secure input acquisition, logical operation, and secure output cutoff. However, in actual debugging and maintenance, engineers often encounter problems such as project failure to load, non-conductive safety outputs, and display screen errors. This article will take PNOZ m B0 as the object, and provide a systematic troubleshooting and debugging method based on its hardware characteristics, installation specifications, project download process, and diagnostic functions.

Understanding PNOZ m B0: Core Features and Security Levels

Understanding the basic capabilities of the equipment is crucial before starting to troubleshoot. PNOZ m B0 is a configurable safety controller base unit, whose main features include:

Safe output: 4 semiconductor safe outputs (O0-O3), each with a rated current of 2A, supporting resistive, capacitive, and inductive loads. The highest safety level can reach PL e of EN ISO 13849-1 and SIL CL 3 of EN 62061.

Safety inputs: 12 dedicated safety inputs that can be connected to emergency stop buttons, safety door switches, dual hand buttons, light curtains, enable switches, etc.

Configurable I/O: 8 terminals that can be configured as input or auxiliary output, and 4 terminals that can be configured as auxiliary output or test pulse output.

Test pulse output: 4 test pulse outputs (T0 – T3), used for monitoring the short circuit of the input circuit.

Project storage: Secure projects must be saved using a chip card (8kByte or 32kByte) and loaded onto the device via a knob.

Diagnosis and Display: Equipped with a backlit LCD display screen and multiple LEDs (PWR, RUN, DIAG, FAULT, I FAULT, O FAULT), supporting local error stack queries.

The device adopts a dual microcontroller redundant architecture and is equipped with periodic output open circuit testing to ensure that safety functions remain effective in the event of a single component failure. Any modification or replacement involving safety features must undergo a complete functional test.

Key points during the installation phase: avoiding fundamental errors

A significant portion of the on-site malfunctions are caused by non-standard installations. Following the following guidelines can significantly reduce the difficulty of subsequent debugging.

2.1 Installation and heat dissipation of control cabinet

PNOZ m B0 must be installed vertically on a horizontal guide rail (with ventilation ducts facing up/down) and installed in a control cabinet with a minimum protection level of IP54. The following minimum spacing (in millimeters) must be maintained:

Up and down with other devices: ≥ 40 mm (to ensure air convection)

Left and right compared to other devices: ≥ 20 mm

It should be noted that if installed with the minimum spacing, it will be very difficult to plug and unplug the chip card from above. Therefore, it is recommended to reserve more space or remove the base from the guide rail when replacing the chip card.

In strong vibration environments (such as stamping equipment), additional fixed brackets or end corner fixing devices should be used, and relying solely on guide rail buckles may not be sufficient for long-term fixation.

2.2 EMC and Grounding Requirements

In order to meet electromagnetic compatibility, the installation guide rail must be connected to the grounding bar of the control cabinet with low impedance. This can effectively discharge high-frequency interference currents. In addition, static discharge (such as touching grounded metal) must be carried out before contacting the equipment to prevent static electricity from damaging internal components.

2.3 Connection of Expansion Modules

If I/O expansion is required, the expansion module must be installed on the left or right side of the base in the order configured in PNOZmulti Configurator (depending on the type). Modules are connected using jumper wires, and unused interfaces must be plugged in with a Terminator resistor. Important note: Before connecting or disconnecting the expansion module, all power sources must be cut off.

Wiring and Power Supply: The Most Common Error Points

The power supply of PNOZ m B0 is divided into two independent power terminals:

System power supply (A1/A2): Provides power to the CPU and internal logic. Voltage DC 24V, allowable fluctuation -20%/+25% (i.e. 19.2V-30V). The maximum continuous current is 1.6A, and the surge current is 3A.

Semiconductor output power supply (+24V/0V): provides safe power supply for O0-O3 output. Same DC 24V, allowing the same fluctuation, the maximum continuous current needs to be calculated based on the load (but not exceeding the total current limit).

Key points:

Even if semiconductor output is not used, power must be supplied to the output power terminal, otherwise the safe output cannot conduct.

Two power supplies can share the same 24V power supply or use two independent power supplies separately (in this case, the two are electrically isolated). But the safety system and input circuit must be powered by the same power source (usually shared with the system power source).

The test pulse output terminals (T0-T3) can only be used to test input circuits (such as detecting short circuits in input lines). It is strictly prohibited to directly drive any load (relays, indicator lights, etc.), otherwise it will trigger the "FAULTRAY TEST PULSE" error.

Inductive loads (contactor coils, etc.) must be externally equipped with freewheeling diodes or RC absorption circuits, otherwise the high-voltage back electromotive force generated during shutdown may damage the semiconductor output.

The test pulse cable should not be parallel to the actuator cable in the same unshielded multi-core cable. Suggest separate wiring.

Typical phenomena caused by wiring errors

The safety output is always OFF: check if the output power is powered on; Check if the project is loaded correctly; Check if the feedback loop (if any) is closed correctly.

The LED "O FAULT" lights up: indicating an external output error, such as a short circuit, overload, or connection of an unacceptable capacitive load to the output terminal.

The LED "I FAULT" lights up: indicating an external input error, such as a wiring error, a test pulse circuit fault, or a partial action of one input (such as a dual channel emergency stop with only one closed).

Project Download and Chip Card Operation: Process and Troubleshooting

PNOZ m B0 does not retain the project itself. Every time it is powered on, it reads the configuration from the inserted chip card. Therefore, the condition of the chip card directly determines whether the device can operate.

4.1 Correct download steps

Confirm that the system power has been disconnected.

Insert the chip card with clean, static free fingers (pay attention to direction and do not bend).

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

Press and hold the knob for 3-8 seconds, and the device will start copying the items from the chip card to the internal memory. Please do not turn off the power during this period.

After success, the RUN LED stays on and switches to the input/output status screen.

4.2 Download via USB

You can also use a Mini USB cable (Pilz order number 312 992 or 312 993) to connect the computer to the base. At this point, the chip card still needs to be inserted (as a storage medium), and then the download command should be executed in the PNOZmulti Configurator. This method is suitable for frequent program modifications during the debugging phase.

4.3 Common chip card related faults

Possible causes and solutions for error messages

CHIP CARD ? Check if the contact surface of the chip card is dirty or scratched when the card is not inserted, blank, or unreadable; Reinsert; Write the project using a new card

The project in the FAULTRAY PROJECT card is damaged or incompatible with the current device firmware. Use a newer version of the Configurator to regenerate the project and download it again to the chip card

After the project is loaded, the device shows no response. If the knob is not held down for a sufficient amount of time, power it back on. Hold down the knob for about 5 seconds until the loading progress is displayed

The display screen shows an error message of "CRC". If the checksum does not match, regenerate and download the item to ensure that the computer item matches the card

Important: The power must be turned off before inserting or removing the chip card. Do not bend the card body, otherwise it may damage the contact spring. When not in use for a long time, it is recommended to store the chip card separately in an anti-static bag.

LED indicator light diagnosis: quickly locate fault levels

The front of PNOZ m B0 has multiple dual color/monochrome LEDs, which can be combined to quickly determine the fault range. The following table summarizes the key states:

The meaning and action of LED (PWR, RUN, DIAG, FAULT, I FAULT, O FAULT)

RUN is off, FAULT is flashing. The user program has been deleted - please download the project again

FAULT stays on, DIAG flashes, external errors cause safety status: such as unplugged chip card, feedback loop disconnection, abnormal test pulse

I FAULT constantly on input external error (does not affect safety forced shutdown): If the dual channel input part is activated, the wiring needs to be checked

O FAULT constantly on output external error (does not affect safety shutdown): such as safety output short circuit or feedback input fault

FAULT flashing and abnormal I/O status display internal hardware error - replace base unit

PWR is normal, RUN is turned off and the device is in STOP state - it may be that the project is not loaded or there is a serious error

During the debugging phase, the most common occurrence is when I and O FAULT light up but the device does not output. At this point, you should use the knob to enter the diagnostic menu and view detailed error text (see below).

Knob operation and display screen diagnosis: obtaining accurate error information

The LCD display screen and rotating press knob of PNOZ m B0 are powerful tools for on-site diagnosis, and can read error stacks without the need for a computer.

6.1 Basic Menu Navigation

Rotate knob: Move the cursor between different menu items (>symbol indicates current position).

Press the knob: Select the currently highlighted menu item.

The main interface usually displays the input/output status (dot matrix on X1~X4 terminals). Rotate the knob to enter in sequence:

ERROR: Display current unconfirmed error messages (such as "E-STOP pressed" or "FEED BACK LOOP").

PROJECT INFO: View project name, CRC, and creation date.

SHOW DEVICE INFO: View the firmware and hardware versions of the base and expansion module.

SHOW Operating INFO: Real time display of cycle time, power supply voltage, internal temperature, etc.

SHOW ERROR STACK: Enter the error stack (up to 64 historical records).

RESET PROJECT? Delete items from the base memory (restore to factory empty state).

STOP Device? Force the device to switch to STOP state (safety output turned off).

6.2 Common Error Message Analysis

According to the operation manual, the following are the most common error texts and their countermeasures:

Solution for displaying incorrect meanings

The items in the FAULTRA PROJECT chip card are damaged or incompatible. Please recompile and download them to the new or original card in the Configurator (format first)

CHIP CARD ? No chip card detected or invalid card data cleaning chip contacts; Replace the chip card; Confirm that the card has been correctly inserted into the bottom

FAULTRA TEST PULSE Test for abnormal pulse circuit (usually short circuited to high or low level) Check the wiring of T0 – T3 terminals to ensure that only the input circuit is connected and not short circuited to other power sources

PARTALLY OPERATED safety input group (such as dual channel emergency stop) only effectively checks whether the two input channels are in the same state; Search for broken wires or poor contacts in the circuit

FEED BACK LOOP feedback loop input (such as contactor auxiliary contacts) status does not match expectations. Check if the external contactor is properly engaged and if the feedback wiring is correctly connected to the IM16 and other feedback input terminals

Measure if the voltage at the+24V/0V terminal of the LOAD SUPERY semiconductor output power supply is within the range of 19.2-30V due to abnormal voltage; Check the power capacity

Supply LOW/HIGH system power supply voltage exceeds tolerance measurement A1-A2 voltage, adjust or replace power supply if necessary

Improve cabinet heat dissipation by installing fans or air conditioning when the ambient temperature exceeds the range of -10 ℃ to+70 ℃

Check if the actual hardware configuration of CONFIGURATION is inconsistent with the project configuration to see if the wrong extension module has been inserted; Is the sequence correct; Is there a lack of terminal resistance

6.3 Usage of Error Stack

After entering SHOW ERROR STACK, the display screen lists error entries in reverse chronological order (latest on top). Each one contains: serial number, error level (EC), error message (EI), error number (EN), and error parameter (PA). These codes can be provided to Pilz technical support for deeper analysis. Ordinary maintenance personnel can make preliminary judgments based on a brief description of the erroneous text.

To exit the error stack, simply rotate the knob to return to the upper menu.

Functional testing and security confirmation: non skipped steps

According to safety standards, a complete functional test must be performed after any of the following operations:

Replace chip card

I downloaded a new project via USB

Implemented 'RESET PROJECT' to delete internal projects and reload

Replaced the base unit or expansion module

Functional testing should include at least:

Enable safety input (such as releasing emergency stop button, closing safety door), and confirm that the corresponding safety output can conduct (load energized).

Trigger safety input (press emergency stop, open safety door), confirm that the safety output is cut off within the specified system response time (load power loss).

For dual channel inputs, simulate a single channel fault (such as resetting only one channel) and confirm that the safety output is not conducting.

Check that the feedback loop (such as the auxiliary contact of the contactor) is consistent with the actual action of the main contact.

If any item in the test does not match, the equipment must not be put into use and the wiring and project configuration must be rechecked.

Device Reset and Project Deletion: When to Use

8.1 Device Reset

When the device enters a safe shutdown state due to an error (such as a feedback loop error) and the external fault has been resolved, the device needs to be reset to restore normal operation. The reset method is:

Press and hold the knob for 3-8 seconds on the normal display interface. The device will restart and reload the project.

If the error still exists, the display screen will report the error again, and further investigation is needed at this time.

8.2 Project deletion

Select menu RESET PROJECT? And confirm that the items in the base memory will be cleared (but the items in the chip card will not be affected). The next time the device is powered on, it will prompt that there are no items and it needs to be reloaded. This operation is applicable to:

Replaced chip cards with different configurations

Need to completely clear the device for new debugging

The project file is damaged and cannot be overwritten

Technical parameter quick search and replacement suggestions

When suspecting that the hardware itself is damaged, the following key parameters can be referred to for judgment:

Parameter values

System power supply voltage 24V DC (-20%/+25%)

Output power supply voltage 24V DC (-20%/+25%)

Safe output maximum current per channel 2.5A (continuous), transient 12A

Safe output maximum capacitive load of 1 μ F (exceeding this may result in incorrect shutdown)

Safe output shutdown delay (typical) 1 ms

Output disconnect time during self check ≤ 330 μ s

Input delay (maximum) 2 ms

Processing time 30 ms

Working temperature -10 ℃...+70 ℃

Protection level IP20 (to be installed in cabinets above IP54)

Dimensions (height x width x depth) 101.4 x 45 x 120 mm

Weight 235 g

If it is confirmed that there is an internal hardware malfunction in the base unit (such as FAULT being constantly on and unable to be eliminated through project loading, or the knob not responding), the PNOZ m B0 with the same model order number 772100 must be replaced. After replacement, simply insert the original chip card into the new base and load the project, without the need for reconfiguration (provided that the expansion module configuration remains unchanged).