Pilz PSS SB HYD, Basic license User Manual

Programmable Safety Systems

PSS-Range

PSS Standard Function Blocks

MBS Hydraulic Presses

Version 3.2

Operating Manual

Item No. 19 203-07

The spirit of safety.

All rights to this manual are reserved by the publishers. Copies may be made for internal purposes.

While every effort has been made to ensure that the information in this manual is accurate, no responsibility can be accepted for errors or omissions contained within it.

We reserve the right to amend specifications without notice. We are grateful for any feedback on the contents of this manual.

The names of products, goods and technologies used in this manual are trademarks of the respective companies.

Contents

									Introduction	1-1
									MBS Modular Block System	1-2
									Categories/requirement classes	1-3
									Overview of manual	1-4
									Definition of symbols	1-5
									Terminology	1-6
									Overview	2-1
									Software package	2-1
									Range	2-2
									Safety	3-1
									Safety guidelines	3-1
									Use of qualified personnel	3-1
									Warranty and liability	3-1
									Application guidelines	3-2
									Standards	3-3
									Fault detection	3-4
									Fault detection techniques	3-5
									Feasibility test	3-5
									Pulsed input signals	3-6
									Self test on the outputs	3-6
									Fault prevention	3-6
									Intended Use	4-1
									System software	4-1
									Intended use of the standard
									function blocks	4-2
									SB051: Operating mode selector switch 1 from 8	4-2
									SB052: Operating mode selector switch 2 from 6	4-3
									SB059: Two-hand monitoring	4-4

Modular Block System: Hydraulic Presses

1

Contents

									SB061: Emergency stop monitoring	4-4
									SB063: Emergency stop monitoring	4-5
									SB064: Safety gate monitoring	4-6
									SB065: Feedback loop monitoring	4-7
									SB066: Safety gate monitoring	4-8
									SB067: Feedback loop monitoring	4-8
									SB068: Monitoring ESPE/AOPDs with guarding and control function	4-9
									SB069: Monitoring ESPE/AOPDs with guarding function	4-10
									SB070: Initialisation of administration data block (DB015)	4-11
									SB071: Initialisation of administration data blocks
									(DB015/DB016/DB017)	4-11
									SB072: Temporary suspension of safety functions	4-12
									SB075: Controlling and monitoring safety gates with guard locking	4-12
									SB086: Overrun control on linear-driven presses	4-13
									SB087: Driving/monitoring the position of a single hydraulic valve	4-14
									SB088: Driving/monitoring the position of a dual hydraulic valve	4-14
									SB089: Driving/monitoring the position of two hydraulic valves	4-16
									SB092: Enable switch	4-17
									SB097: Monitoring muting lamps	4-18

									MBS Basics	5-1
									Block design	5-1
									Structure	5-1
									Formal parameters and actual parameters	5-2
									Administration data blocks DB015, DB016 and DB017	5-3
									Structure of the administration data blocks	5-3
									Blocks contained in the administration data blocks	5-5
									Input parameter SSNR	5-7
									Fault diagnostics	5-9
									Error types	5-9
									Fault diagnostics using the administration data blocks	5-10
									Temporary flag range in MBS blocks	5-11
									Output parameter FG/ENBL	5-11
									Assignment of input and output parameters	5-12
									Minimum scan time	5-12
									Global parameters	5-13

2	Modular Block System: Hydraulic Presses

									Standard Function Blocks	6-1
									Guidelines for selecting standard function blocks	6-1
									Emergency stop monitoring	6-1
									SB061 NA_1	6-1
									SB063 E-STOP	6-1
									Safety gate monitoring	6-2
									SB066 ST-K4	6-2
									SB064 S-GATE	6-3
									Feedback loop monitoring	6-3
									SB067 RFK_K4	6-3
									SB065 FBL	6-4
									Initialisation of administration data blocks	6-4
									SB070 INIT_MBS	6-4
									SB071 INIT_MBS	6-5
									SB051: Operating mode selector switch 1 from 8	6-6
									Block header	6-6
									Input parameters	6-6
									Output parameters	6-7
									Error messages	6-8
									Global parameters used in administration data block DB015	6-9
									Blocks required	6-10
									SB052: Operating mode selector switch 2 from 6	6-10
									Block header	6-10
									Input parameters	6-10
									Output parameters	6-12
									Error messages	6-13
									Global parameters used in administration data block DB015	6-14
									Blocks required	6-14

Modular Block System: Hydraulic Presses

3

Contents

									SB059: Two-hand monitoring	6-16
									Block header	6-16
									Input parameters	6-16
									Output parameters	6-20
									Error messages	6-20
									Global parameters used in administration data block DB015	6-22
									Blocks required	6-22
									SB061: Emergency stop monitoring

Category 4	6-24
Block header	6-24
Input parameters	6-24
Output parameters	6-25
Error messages	6-25
Global parameters used in administration data block DB015	6-27
Blocks required	6-27
SB063: Emergency stop monitoring

Category 4	6-28
Block header	6-28
Input parameters	6-28
Output parameters	6-29
Function test	6-29
Error messages	6-30
Global parameters used in the administration data blocks	6-31
Blocks required	6-31
SB064: Safety gate monitoring	6-32
Block header	6-32
Input parameters	6-32
Output parameters	6-34
Functions	6-35
Error messages	6-38
Global parameters used in the administration data blocks	6-39
Blocks required	6-39
SB065: Feedback loop monitoring	6-40
Block header	6-40
Input parameters	6-40
Output parameters	6-41
Functions	6-42
Error messages	6-43
Global parameters used in the administration data blocks	6-45
Blocks required	6-45

4	Modular Block System: Hydraulic Presses

									SB066: Safety gate monitoring	6-46
									Block header	6-46
									Input parameters	6-46
									Input circuitry	6-47
									Output parameters	6-48
									Functions	6-48
									Error messages	6-52
									Global parameters used in administration data block DB015	6-53
									Blocks required	6-53
									SB067: Feedback loop monitoring on contactors	6-54
									Block header	6-54
									Input parameters	6-54
									Output parameters	6-54
									Error messages	6-55
									Global parameters used in administration data block DB015	6-56
									Blocks required	6-56
									SB068: Monitoring ESPE/AOPDs with
									guarding and control function	6-58
									Block header	6-58
									Input parameters	6-58
									Wiring the input parameters	6-62
									Output parameters	6-62
									Function	6-63
									Cycle modes	6-65
									Error messages	6-65
									Global parameters used in administration data block DB015	6-67
									Blocks required	6-67
									Diagrams for ESPE/AOPD	6-68
									Timing diagram for “guard only” mode of ESPE/AOPD	6-68
									Timing diagram for “double break” mode of ESPE/AOPD	6-70
									SB069: Monitoring ESPE/AOPDs with
									guarding and control function	6-72
									Block header	6-72
									Input parameters	6-72
									Wiring the input parameters	6-74
									Output parameters	6-74
									Function	6-75
									Error messages	6-76

Modular Block System: Hydraulic Presses

5

Contents

									Global parameters used in administration data block DB015	6-77
									Blocks required	6-77
									Timing diagram	6-78
									SB070: Initialisation of administration data block DB015	6-80
									Block header	6-80
									Input parameters	6-80
									Function	6-80
									Error messages	6-82
									Blocks required	6-82
									SB071: Initialisation of administration data blocks	6-84
									Block header	6-84
									Input parameters	6-84
									Function	6-84
									Error messages	6-86
									Blocks required	6-86
									SB072: Temporary suspension of safety
									functions (ESPE/AOPD muting)	6-88
									Block header	6-88
									Input parameters	6-88
									Wiring the input parameters	6-91
									Output parameters	6-91
									Wiring the output parameters	6-92
									Operating modes	6-92
									Terminology	6-92
									Sequential muting mode (muting when entering the danger area)	6-93
									Parallel muting mode (muting when leaving the danger area)	6-95
									Parallel muting mode (muting when entering and leaving the
									danger area)	6-97
									Safety guidelines	6-99
									Error messages	6-100
									Global parameters used in administration data block DB015	6-102
									Blocks required	6-102
									Cycle diagrams	6-103
									Parallel muting cycle	6-103
									Sequential muting cycle	6-104
									SB075: Controlling and monitoring safety gates with
									guard locking	6-106
									Block header	6-106
									Input parameters	6-106
									Input circuitry	6-110

6	Modular Block System: Hydraulic Presses

									Output parameters	6-110
									Operating modes	6-112
									Procedures	6-115
									Additional safety guidelines	6-116
									Error messages	6-117
									Global parameters used in administration data block DB015	6-119
									Blocks required	6-119
									SB086: Overrun control on linear-driven presses	6-120
									Block header	6-120
									Input parameters	6-120
									Output parameters	6-122
									Procedures	6-122
									Timing diagram	6-125
									Error messages	6-125
									Global parameters used in administration data block DB015	6-126
									Blocks required	6-126
									SB087: Driving/monitoring the position of a single
									hydraulic valve (poppet and directional control
									valve)	6-128
									Block header	6-128
									Input parameters	6-128
									Output parameters	6-129
									Function	6-130
									Safety guidelines for input parameters TOn and TOff	6-132
									Settings for the parameters TOn and TOff	6-133
									Error messages	6-134
									Global parameters used in administration data block DB015	6-135
									Blocks required	6-135
									SB088: Driving/monitoring the position of a dual
									hydraulic valve (poppet and directional control
									valve)	6-136
									Block header	6-136
									Input parameters	6-136
									Output parameters	6-138
									Function	6-139
									Safety guidelines for input parameters TOn and TOff	6-141
									Settings for the parameters TOn and TOff	6-143
									Error messages	6-144
									Global parameters used in administration data block DB015	6-146
									Blocks required	6-146
Modular Block System: Hydraulic Presses										7

Contents

									SB089: Sequential driving/monitoring the position
									of two hydraulic valves (poppet and directional
									control valves)	6-148
									Block header	6-148
									Input parameters	6-148
									Output parameters	6-150
									Function	6-151
									Safety guidelines for input parameters TOn and TOff	6-153
									Settings for the parameters TOn and TOff	6-154
									Error messages	6-155
									Global parameters used in administration data block DB015	6-157
									Blocks required	6-157
									SB092: Enable switch	6-158
									Block header	6-158
									Input parameters	6-158
									Output parameters	6-159
									Function	6-160
									Switching diagrams	6-161
									Error messages	6-163
									Global parameters used in administration data block DB015	6-163
									Blocks required	6-163
									SB097: Monitoring muting lamps	6-164
									Block header	6-164
									Input parameters	6-164
									Output parameters	6-165
									Wiring the output parameters	6-166
									Wiring diagram	6-166
									Function	6-166
									Guidelines for the design and layout of muting lamps	6-167
									Error messages	6-168
									Global parameters used in administration data block DB015	6-169
									Blocks required	6-169
									Timing diagrams	6-170

									Link Blocks	7-1
									Check list	7-1

8	Modular Block System: Hydraulic Presses

									Examples	8-1
									Application and parameters of individual blocks	8-2
									Emergency stop monitoring
									with manual start (start-up and operation), category 4	8-2
									Emergency stop monitoring
									with automatic start-up, manual start (operation)
									and function test, category 4	8-4
									Feedback loop monitoring
									Shutdown with two contactors connected in series,
									category 4	8-6
									Feedback loop monitoring
									Shutdown with two main contactors connected in series and
									pulsed outputs, category 4	8-8
									Feedback loop monitoring (selective shutdown),
									category 4	8-10
									Emergency stop monitoring with monitoring of feedback loop,
									category 4	8-14
									Safety gate monitoring
									with manual start and manual restart, category 2	8-16
									Safety gate monitoring
									with automatic start and manual restart, category 2	8-20
									Safety gate monitoring
									with manual start and manual restart, category 4	8-24
									Safety gate monitoring
									with automatic start and manual restart,
									category 4	8-28
									Safety gate monitoring
									with manual start and manual restart, category 4	8-32
									Safety sensors PSEN 2.1p-10 and PSEN 2.1p-11
									with block SB066 (ST_K4)	8-36
									ESPE/AOPD in guard mode with automatic function test
									(SB068)	8-40
									ESPE/AOPD in single break mode with cycle reset via a pulse at
									top dead centre (TDC)	8-42
									ESPE/AOPD in guard mode with automatic function test
									(SB069)	8-44
									Monitoring muting lamps	8-46
									Safety gate monitoring with guard locking, automatic start and
									manual restart, category 4	8-48
Modular Block System: Hydraulic Presses										9

Contents

									Appendix	9-1
									Assignment table
									Category and requirement class	9-1
									Standard function blocks: current versions	9-2
									Changes to the standard function blocks	9-3
									Changes to the operating manual	9-15
									Allocation of safety subroutine numbers -
									enable flags	9-17

10	Modular Block System: Hydraulic Presses

Modular Block System: Hydraulic Presses

11

Introduction

This manual describes how to manage the standard function blocks in the

“MBS Hydraulic Presses” software package in accordance with their intended use.

Standard function blocks in the “MBS Hydraulic Presses” package are part of the Pilz MBS Modular Block System. They can be used in the failsafe section of a PSS-range programmable safety system.

To fully understand this manual you will need to be conversant with the information found in the general documentation for the PSS-range (System Manual, Installation Manual for the modular/compact PSS, PSS

SW PG Programming Manual/PSS WIN-PRO Programming Manual).

In particular you should refer to the following documents from the System

Manual:

•Safety Manual

•FS System Description

•Error List

To fully understand the bus-specific requirements and correlations for SafetyBUS p applications you will need some knowledge of the design and management of SafetyBUS p.

Knowledge of the safety regulations for the particular area of application is assumed.

This installation manual is intended for instruction and should be retained for future reference.

Modular Block System: Hydraulic Presses

1-1

Introduction

MBS Modular Block System

Safety-related areas can be equipped with a multitude of safety devices such as E-STOPs, safety gates, light barriers etc. Safety devices are required in various quantities and combinations, depending on the object requiring protection. The Pilz MBS Modular Block System was developed to drive the various safety devices and to carry out process engineering functions, helping users to save time and money.

The MBS consists of individual standard function blocks (SBs), which are geared specifically towards the relevant safety device or process engineering function. It allows standard function blocks to be used in any combination. The standard function blocks can be combined in any sequence (max. 600).

Standard function blocks are encoded by an authorised body so that they cannot be modified. If an encoded standard function block is used within an application program, program testing may be restricted to the new parts of the program, considerably reducing the test time.

1-2	Modular Block System: Hydraulic Presses

Categories / requirement classes

EN 954-1 divides safety devices into categories.

All standard function blocks are designed for the highest category permitted for the safety device to be monitored. If safety devices with lower categories are to be monitored, input parameters may be assigned identical inputs (further information can be found in the description for the relevant standard function block).

In process engineering, safety requirements must conform to DIN V 19250

(Basic Safety Requirements for Measurement and Control Protection

Devices).

Requirement classes in accordance with DIN V 19250 may be referred to the categories as per EN 954-1. The Appendix contains a table showing the assignment of category ↔ requirement class.

Modular Block System: Hydraulic Presses

1-3

Introduction

Overview of manual

1Introduction

The chapter you are reading provides an introduction to the Modular

Block System (MBS). It is designed to familiarise you with the contents, structure and specific order of this manual and also contains terminology definitions.

2Overview

This chapter provides information on the most important features of the software package and provides a brief overview of the application range.

3Safety

This chapter must be read as it contains important information on safety regulations.

4Intended Use

This chapter must be read as it contains information on intended use.

5MBS Basics

This chapter explains the basic functions and safety requirements of the MBS.

6Standard Function Blocks

This chapter explains the function of the standard function blocks in the software package.

7Link Blocks

This chapter is designed to help you link the standard function blocks into your project and to commission the safety functions.

8Examples

This chapter is designed to give an overview of how the standard function blocks may be applied and contains typical application examples.

9Appendix

The Appendix contains a table that explains the relationship between categories and requirement classes, plus a list that documents the current version status of the standard function blocks.

1-4	Modular Block System: Hydraulic Presses

Definition of symbols

Information in this manual that is of particular importance can be identified as follows:

DANGER!

This warning must be heeded! It warns of a hazardous situation that poses an immediate threat of serious injury and death and indicates preventive measures that can be taken.

WARNING!

This warning must be heeded! It warns of a hazardous situation that could lead to serious injury and death and indicates preventive measures that can be taken.

CAUTION!

This refers to a hazard that can lead to a less serious or minor injury plus material damage, and also provides information on preventive measures that can be taken.

NOTICE

This describes a situation in which the product or devices in its immediate environment could be damaged. It also provides information on preventive measures that can be taken.

INFORMATION

This gives advice on applications and provides information on special features, as well as highlighting areas within the text that are of particular importance.

Modular Block System: Hydraulic Presses

1-5

Introduction

Terminology

•The term “input” is frequently abbreviated to “I” (e.g. I-Parameter).

•The term “output” is frequently abbreviated to “O” (e.g. O-Parameter).

•The term “PSS” is always used when the description is valid for all applicable PSS programmable safety systems. If the description only relates to a specific PSS series, the specific name for that series will be used (e.g. PSS 3000 or PSS SB 3056).

•In this manual, the system software “PSS SW PG” and “PSS WIN-PRO” is referred to as “programming device” or “PG”.

1-6	Modular Block System: Hydraulic Presses

Overview

Software package

The “MBS Hydraulic Presses” software package is part of the Pilz MBS Modular Block System. The software package contains all the standard function blocks necessary for electronically-monitored safety devices on distributed automation plants. This includes:

•Monitoring the position of operating mode selector switches for safe mode selection (automatic, manual, cycle mode etc.)

•Monitoring two-hand circuits for simultaneity

•Evaluation of E-STOP buttons, grab wires etc.

•Monitoring safety, maintenance and supply gates

•Monitoring of power contactors through control of the feedback loop

•Controlling and monitoring electrosensitive protective equipment

•Safe, temporary suspension of safety functions (muting mode)

•Driving and monitoring a press safety valve

•Monitoring enable switches

Standard function blocks in the “MBS Hydraulic Presses” software package are used in the failsafe section of a PSS-range programmable safety system.

Modular Block System: Hydraulic Presses

2-1

Overview

Range

The software package consists of:

•The files for the software package on CD and

•An operating manual:

PSS Standard Function Blocks MBS Hydraulic Presses, Version 3.2

The software package on the CD contains the following standard function blocks:

• SB051	BA_1AUS8
	Operating mode selector switch 1 from 8
	(approved safety block)
• SB052	BA_2AUS6
	Operating mode selector switch 2 from 6
	(approved safety block)
• SB059	2_HAND
	Two-hand monitoring
	(approved safety block)
• SB061	NA_1
	Monitoring E-STOP button up to category 4 in accordance with
	EN 954-1, 03/97 and AK 6 in accordance with DIN V 19 250,
	05/94
	(approved safety block)
• SB063	E-STOP
	Monitoring E-STOP button up to category 4 in accordance with
	EN 954-1, 03/97 and AK 6 in accordance with DIN V 19 250,
	05/94
	(approved safety block)
• SB064	S-GATE
	Safety gate monitoring
	(approved safety block)
• SB065	FBL
	Feedback loop monitoring
	(approved safety block)
• SB066	ST-K4
	Safety gate monitoring
	(approved safety block)

2-2	Modular Block System: Hydraulic Presses

• SB067	RFK_K4
	Feedback loop monitoring
	(approved safety block)
• SB068	BWS_AOS
	Monitoring ESPE/AOPD with guarding and control function
	(approved safety block)
• SB069	AOPD_GDO
	Monitoring ESPE/AOPD with guarding function
	(approved safety block)
• SB070	INIT_MBS
	Initialisation of the administration data block (DB015)
	(approved safety block)
• SB071	INIT_MBS
	Initialisation of the administration data blocks (DB015/DB016/
	DB017)
	(approved safety block)
• SB072	MUTING
	Temporary suspension of safety functions
	(approved safety block)
• SB075	GRD_LCK
	Control and monitoring of safety gates with guard locking
	(approved safety block)
• SB086	OVERRUN
	Overrun control on linear-driven presses
	(approved safety block)
• SB087	H_VALV_S
	Control and position monitoring of single hydraulic valves
	(poppet valve and directional control valve)
	(approved safety block)
• SB088	H_VALV_D
	Control and position monitoring of dual hydraulic valves
	(poppet valve and directional control valve)
	(approved safety block)
• SB089	H_VALV_P
	Sequential control and position monitoring of two hydraulic
	valves (poppet valve and directional control valve)
	(approved safety block)

Modular Block System: Hydraulic Presses

2-3

Overview

• SB092 ENBL_DEV

Enable switch (approved safety block)

• SB097 MUT_LAMP

Monitoring muting lamps (approved safety block)

• SB255 System block

SB255 is described in the PSS System Description

2-4	Modular Block System: Hydraulic Presses

Safety

Safety guidelines

These safety guidelines are an important part of this manual. Failure to keep to these guidelines will render all warranty, guarantee and liability claims invalid.

•All health and safety / accident prevention regulations for the particular area of application must be observed.

•Before using one or more of the standard function blocks in this software package, you must perform a safety assessment in accordance with the Machinery Directive.

Use of qualified personnel

The package may only be assembled, installed, commissioned, operated, maintained and decommissioned by qualified personnel who, because they are

•Qualified electrical engineers and/or

•Have received training from qualified electrical engineers

are suitably experienced to operate devices, systems, plant and machinery in accordance with the general standards and guidelines for safety technology.

Warranty and liability

All claims to warranty and liability will be rendered invalid if:

•Standard function blocks are used contrary to the purpose for which they were intended

•Damage can be attributed to not having followed the guidelines in the manual

•Operating personnel are not suitably qualified.

Modular Block System: Hydraulic Presses

3-1

Safety

Application guidelines

•The instructions given in the “Safety Manual” and in the “Installation Manual” must be followed.

•Please read the information in Chapter 4 regarding the intended use of these blocks.

•The use of Pilz SBs does not detract from the fact that it is the responsibility of the user to design appropriate safety systems for plant, machinery and software.

•It is the users' responsibility to determine their application requirements by carrying out a detailed risk analysis, which should take into account relevant regulations and standards, etc.

WARNING!

Please note: To achieve the corresponding category or requirement class, the whole system including all safety-related components (parts, devices, user program etc.) must be included in the assessment. For this reason,

Pilz cannot accept liability for the correct classification into a category or requirement class.

3-2	Modular Block System: Hydraulic Presses

Standards

To use the SBs correctly you will need to have a good knowledge of the relevant standards and directives. The following gives an overview of the most important standards:

• E-STOP circuits	EN 418
• Safety of machinery -
Two-hand controls	EN 574
• Mechanical presses	EN 692
• Hydraulic presses	EN 693
• Hydraulic stamping and bending presses	EN 12 622
• Machinery directive - basic terminology	EN 292-1 and EN 292-2
• Printing and paper machinery	prEN 1010
• Safety gates	EN 1088
• Electrosensitive protective equipment	EN 61 496-1
• Electrical equipment	EN 60 204-1
• Machinery safety	EN 954-1
• Basic Safety Requirements for Mea-
surement and Control Protection Devices	DIN V 19 250
• Electrical equipment on firing plants	prEN 50 156-1

Please note this is not an exhaustive list of safety standards and directives.

Modular Block System: Hydraulic Presses

3-3

Safety

Fault detection

The detection of errors and defects is an important function of the PSS, in addition to pure control tasks.

Potential faults are subdivided into:

•Errors in the system hardware and wiring errors in the periphery units:

-Errors in the system hardware are automatically detected and managed by the PSS

-If test signals are used, wiring errors in the periphery units will automatically be detected and managed by the PSS.

Users do not need to take this type of error into account within the application program (additional information can be found in the PSS “System Description”).

•Feasibility errors and functional errors in the process periphery units (input devices, actuators, wiring etc.).

These errors must be detected and managed through the PSS control program.

WARNING!

It is particularly important to detect open circuits and shorts within the safety circuits (e.g. two-hand, E-STOP etc.)

It is the responsibility of the user to select and apply an appropriate fault detection system.

3-4	Modular Block System: Hydraulic Presses

Fault detection techniques

Various options are available to the user to help detect and rectify errors in the process periphery units:

•Errors can be detected via the feasibility checks in the application program, e.g. by using redundant input devices.

•Errors can be detected by pulsing the signal lines using the test pulses from the PSS DI2O T module.

•Errors can be detected by using the automatic tests in the output modules.

•Avoid potential errors by using appropriate wiring.

Additional information on how to exclude potential errors can be found in the directive VDI 2854 (safety requirements on automated manufacturing systems).

Feasibility test

Redundant input devices for safety functions must undergo a feasibility test within the application program.

Example:

A two-hand button has a N/C and a N/O contact. Once the application program has detected the open N/C contact, it must check that the N/O contact closes within an appropriate period of time. The function test must be carried out for all possible combinations of the two contacts.

The plant must be stopped immediately if a feasibility error occurs. Similar tests will also be required for other input devices.

If safety valves have feedback contacts, these must be evaluated accordingly.

Modular Block System: Hydraulic Presses

3-5

Safety

Pulsed input signals

Input devices for inputs with infrequent operation (e.g. E-STOP, off buttons, etc.) must be pulsed using test signals. The connection of test pulses to input devices is described in the “Installation Manual”.

Test pulses should also be used for input devices which have an important safety function and frequent operation (e.g. two-hand, camshaft etc.).

Self test on the outputs

PSS output modules regularly carry out function tests. Using these tests, dual-pole switching output modules on the PSS are automatically able to detect and deal with open circuits, short circuits and external power sources in the periphery wiring.

Single-pole switching output modules can detect short circuits but not open circuits.

Fault prevention

Not all potential faults can be detected and managed. Such faults must be excluded by suitable wiring.

Example: If the feed to the input device and the feedback from the input device to the input use the same multicore cable, a short circuit between the two wires could short out the input device. Such a fault would go undetected.

3-6	Modular Block System: Hydraulic Presses