Siemens S7-1500 PROFIBUS User manual

SIMATIC CM 1542-5
SIMATIC NET
S7-1500 - PROFIBUS
SIMAT
IC CM 1542-5
Operating Instructions
CM 1542-5, firmware V2.0 (6GK7542-5DX00-0XE0)
CM 1542
-5, firmware V3.0 (6GK7542-5DX10-0XE0)
01/2023
C79000
-G8976-C290-07
Preface
Application and functions
1
Installation, wiring,
commissioning, operation,
disassembly
2
Configuration, program
blocks
3
Diagnostics and upkeep
4
Technical specifications
5
Approvals
6
Dimension drawings
7

Siemens AG
Digital Industries
Postfach 48 48
90026 NÜRNBERG
GERMANY
C79000-G8976-C290-07
Ⓟ
01/2023 Subject to change
Copyright © Siemens AG 2013 - 2023.
All rights reserved
Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
indicates that minor personal injury can result if proper precautions are not taken.
NOTICE
indicates that property damage can result if proper precautions are not taken.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will
be used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to
property damage.
Qualified Personnel
The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation, in particular its warning notices and safety instructions.
Qualified personnel are those who, based on their training and experience, are capable of identifying risks and
avoiding potential hazards when working with these products/systems.
Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended
or approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and
maintenance are required to ensure that the products operate safely and without any problems. The permissible
ambient conditions must be complied with. The information in the relevant documentation must be observed.
Trademarks
All names identified by ® are registered trademarks of Siemens AG. The remaining trademarks in this publication
may be trademarks whose use by third parties for their own purposes could violate the rights of the owner.
Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software
described. Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the
information in this publication is reviewed regularly and any necessary corrections are included in subsequent
editions.

SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 3
Preface
Article number, validity and product names
This description contains information on the following product:
•CM 1542-5
Article number 6GK7 542-5DX00-0XE0
Hardware version 1
Firmware version V2.0.24
•CM 1542-5
Article number 6GK7 542-5DX10-0XE0
Hardware version 1
Firmware version V3.0
Communications modules for connecting S7-1500 to PROFIBUS DP
View of the module
①
LEDs
②
Type plate
③
PROFIBUS interface: 1 x 9-pin D-sub female connector (RS-485)
Figure 1 CM 1542-5 with closed (left) and open (right) front cover

Preface
SIMATIC CM 1542-5
4Operating Instructions, 01/2023, C79000-G8976-C290-07
Abbreviations and reference to the module version
•CM / module / device
These terms are used in the following instead of the complete product designation. In this
case, the information applies equally to both firmware versions or hardware product
versions of the module.
If the data of the two devices differs, the firmware version or the hardware version of the
respective device is explicitly stated.
•STEP 7
The name STEP 7 is used to mean the STEP 7 Professional configuration tool.
Purpose of the documentation
This device manual supplements the system manual of the automation system S7-1500 and
the function manuals. All functions that go beyond the system are described in the system
manual.
With the information in this manual and the system manual, you will be able to commission
the CM 1542-5 communications module.
New in this edition
•New module with new article number, see above.
•New firmware versions with the following extensions:
–Setting the PROFIBUS address from the user program, see section Setting the PROFIBUS
address from the user program (Page 29).
–Improvements of the operating behavior
•New approvals: CCC / UKEX
•Editorial revision
Replaced edition
Edition 06/2021
New in edition 06/2021: Additions for FDL communication in the extended LSAP range 1...56,
see section Configuration of the extended LSAP area (Page 30).
Manual on DVD
You will find the manual on the DVD supplied with the product. This DVD contains the
product manuals valid at the time it is created.
Current manual edition on the Internet
You will also find the current version of this manual on the Internet pages of Siemens
Industry Online Support:
Link: (https://support.industry.siemens.com/cs/ww/en/ps/15671/man)

Preface
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 5
License conditions
Note
Open source software
The product contains open source software. Read the license conditions for open source
software carefully before using the product.
You will find license conditions in the following document on the supplied data medium:
•OSS_CM15425_86.pdf
•OSS_CM15425_99.pdf
Firmware
The firmware is signed and encrypted. This ensures that only firmware created by Siemens
can be downloaded to the device.
Note on firmware/software support
Check regularly for new firmware/software versions or security updates and apply them. After
the release of a new version, previous versions are no longer supported and are not
maintained.
Security information
Siemens provides products and solutions with industrial security functions that support the
secure operation of plants, systems, machines and networks.
In order to protect plants, systems, machines and networks against cyber threats, it is
necessary to implement – and continuously maintain – a holistic, state-of-the-art industrial
security concept. Siemens’ products and solutions constitute one element of such a concept.
Customers are responsible for preventing unauthorized access to their plants, systems,
machines and networks. Such systems, machines and components should only be connected
to an enterprise network or the internet if and to the extent such a connection is necessary
and only when appropriate security measures (e.g. firewalls and/or network segmentation)
are in place.
For additional information on industrial security measures that may be implemented, please
visit
Link: (http://www.siemens.com/industrialsecurity)
Siemens’ products and solutions undergo continuous development to make them more
secure. Siemens strongly recommends that product updates are applied as soon as they are
available and that the latest product versions are used. Use of product versions that are no
longer supported, and failure to apply the latest updates may increase customers’ exposure to
cyber threats.
To stay informed about product updates, subscribe to the Siemens Industrial Security RSS
Feed under
Link: (https://www.siemens.com/cert)

Preface
SIMATIC CM 1542-5
6Operating Instructions, 01/2023, C79000-G8976-C290-07
Observe the following security recommendations to prevent unauthorized access to the
system.
•Evaluate your plant as a whole in terms of security. Use a cell protection concept with
suitable products.
•Keep the firmware up to date. Check regularly for security updates of the firmware and
use them.
•Restrict physical access to the device to qualified personnel.
•Configure a protection level of the CPU.
Documentation guide
The documentation of the SIMATIC products has a modular structure and covers topics
relating to your automation system.
The complete documentation for the S7-1500 system consists of a system manual, function
manuals and device manuals.
The STEP 7 information system (online help) also supports you in configuring and
programming your automation system.
Overview of the documentation on communication with S7-1500
The following table lists additional documents, which supplement this description of the
CM 1542-5. The documents are available on the Internet.
Table 1 Documentation for the CM 1542-5
Topic
Documentation
Important contents
System
description
S7-1500 automation system
(https://support.industry.siemens.com/cs/ww/e
n/view/59191792) system manual
•Application planning
•Installation
•Connecting
•Commissioning
Module properties Power supplies
(https://support.industry.siemens.com/cs/ww/e
n/ps/13743/man) manual
•Connecting
•Parameter assignment/
addressing
•Interrupts, error messages,
diagnostics and system
alarms
•Technical specifications
•Dimension drawing
Signal modules
(https://support.industry.siemens.com/cs/ww/e
n/ps/13721/man) manual
System
diagnostics
System diagnostics
(https://support.industry.siemens.com/cs/ww/e
n/view/59192926) function manual
•Overview
•Diagnostics evaluation for
hardware/software
Communication
Communication
(https://support.industry.siemens.com/cs/ww/e
n/view/59192925) function manual
•Overview

Preface
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 7
Topic
Documentation
Important contents
Function manual PROFINET with STEP 7
(https://support.industry.siemens.com/cs/ww/e
n/view/49948856)
•PROFINET basics
•PROFINET functions
•PROFINET diagnostics
Function manual PROFIBUS with STEP 7
(https://support.industry.siemens.com/cs/ww/e
n/view/59193579)
•PROFIBUS basics
•PROFIBUS functions
•PROFIBUS diagnostics
Web server
(https://support.industry.siemens.com/cs/ww/e
n/view/59193560) function manual
•Function
•Operation
Interference-free
installation of
control systems
Designing interference-free controllers
(https://support.industry.siemens.com/cs/ww/e
n/view/59193566) function manual
•Basics
•Electromagnetic
compatibility
•Lightning protection
•Housing selection
Memory concept Structure and Use of the CPU Memory
(https://support.industry.siemens.com/cs/ww/e
n/view/59193101) function manual
•Design
•Principle of operation
•Use
Cycle and
response times
Function manual: Cycle and Response Times
(https://support.industry.siemens.com/cs/ww/e
n/view/59193558)
•Basics
•Calculations
Analog value
processing
Function manual: Analog value processing
(https://support.industry.siemens.com/cs/ww/e
n/view/67989094)
•Wiring options
•Tables of measured values
SIMATIC manuals
The current manuals for SIMATIC products are available on the Internet:
Link: (http://www.siemens.com/automation/service&support)
CP/CM documentation on DVD
You can find the documentation on the product and the configuration on the "SIMATIC NET
Manual Collection" or "SIMATIC Communication Products" DVD. This DVD contains the
product manuals valid at the time it is created.
Recycling and disposal
The product is low in pollutants, can be recycled and meets the requirements of the WEEE
directive 2012/19/EU "Waste Electrical and Electronic Equipment".
Do not dispose of the product at public disposal sites. For environmentally friendly recycling
and the disposal of your old device contact a certified disposal company for electronic scrap
or your Siemens contact.
Keep to the local regulations.

Preface
SIMATIC CM 1542-5
8Operating Instructions, 01/2023, C79000-G8976-C290-07
You will find information on returning the product on the Internet pages of Siemens Industry
Online Support:
Link: (https://support.industry.siemens.com/cs/ww/en/view/109479891)
SIMATIC NET glossary
The SIMATIC NET glossary describes terms that may be used in this document.
You will find the SIMATIC NET glossary in the Siemens Industry Online Support at the
following address:
Link: (https://support.industry.siemens.com/cs/ww/en/view/50305045)

SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 9
Table of contents
Preface ................................................................................................................................................... 3
1 Application and functions.................................................................................................................... 11
1.1 Application ........................................................................................................................ 11
1.2 Further functions............................................................................................................... 12
1.3 Configuration limits and performance data......................................................................... 13
1.3.1 Configuration limits - number of CMs................................................................................. 13
1.3.2 Transmission speeds supported.......................................................................................... 14
1.3.3 Characteristic data of the DP interface................................................................................ 14
1.3.4 Characteristic data of FDL communication.......................................................................... 15
1.3.5 Characteristics of S7 communication.................................................................................. 15
1.3.6 Performance data / operation............................................................................................. 16
1.4 Requirements for use......................................................................................................... 16
1.4.1 Usable CPUs....................................................................................................................... 16
1.4.2 Project engineering............................................................................................................ 17
1.4.3 Program blocks.................................................................................................................. 17
1.5 LEDs .................................................................................................................................. 18
1.6 PROFIBUS interface ............................................................................................................ 19
2 Installation, wiring, commissioning, operation, disassembly............................................................. 21
2.1 Important notes on using the device .................................................................................. 21
2.1.1 Notes on use in hazardous areas ........................................................................................ 21
2.1.2 Notes on use in hazardous areas according to ATEX / UKEX / IECEx / CCC-Ex ........................ 22
2.1.3 Notes on use in hazardous areas according to UL HazLoc and FM........................................ 22
2.2 Installation, removal and repairs in hazardous areas ........................................................... 23
2.3 Installing, connecting and commissioning .......................................................................... 25
2.4 Mode of the CPU - effect on the CM.................................................................................... 26
2.5 Disassembly....................................................................................................................... 27
3 Configuration, program blocks............................................................................................................ 29
3.1 Configuration in STEP 7...................................................................................................... 29
3.2 Configuring in third-party systems...................................................................................... 29
3.3 Setting the PROFIBUS address from the user program......................................................... 29
3.4 Configuration of the extended LSAP area............................................................................ 30
3.5 Program blocks for communication and distributed I/O....................................................... 35
3.6 Program blocks for FDL ...................................................................................................... 36
4 Diagnostics and upkeep....................................................................................................................... 43
4.1 Diagnostics........................................................................................................................ 43

Table of contents
SIMATIC CM 1542-5
10 Operating Instructions, 01/2023, C79000-G8976-C290-07
4.1.1 Diagnostics options............................................................................................................ 43
4.1.2 DP slave diagnostics........................................................................................................... 44
4.1.3 Standard diagnostics.......................................................................................................... 45
4.1.4 Device-specific diagnostics in DP-V1................................................................................... 47
4.1.5 DP diagnostics frames when the CPU is in STOP.................................................................. 50
4.2 Maintenance ..................................................................................................................... 50
4.2.1 Update firmware................................................................................................................ 51
4.2.2 Module replacement.......................................................................................................... 53
5 Technical specifications....................................................................................................................... 55
5.1 Technical specifications of the CM (6GK7542-5DX00-0XE0) ............................................... 55
5.2 Technical specifications of the CM (6GK7542-5DX10-0XE0) ............................................... 56
5.3 PROFIBUS interface terminal assignment............................................................................ 57
5.4 Ambient temperature ........................................................................................................ 57
6 Approvals............................................................................................................................................. 59
7 Dimension drawings............................................................................................................................ 65
Index.................................................................................................................................................... 67

SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 11
Application and functions
1
1.1 Application
Application
The communications module CM 1542-5 is intended for operation in an S7-1500 automation
system. The CM 1542-5 allows the connection of an S7-1500 station to a PROFIBUS fieldbus
system.
As an alternative, the CM can be operated in the following modes:
•Class 1 DP master
•DP slave
Supported communications services
In its current configuration, the CM 1542-5 communications module supports the following
communications services:
•PROFIBUS DP master (class 1)
–DP master according to EN 50170, DP-V1
–DP master mode for DP slaves according to PROFIBUS DP-V0 and DP-V1
–DP master mode for Siemens DP slaves
–Direct data exchange (DP slave to DP slave)
As a DP master, the CM 1542-5 is capable of enabling direct data exchange for its
assigned DP slaves.
–SYNC/FREEZE
The outputs or inputs can be synchronized and frozen by the user program using
system function DPSYNC_FR.
•PROFIBUS DP slave
DP slave according to EN 50170, DP-V0 / DP-V1
Note
DP master or DP slave
The CM only supports operation either as DP master or DP slave.
•FDL
The CM handles the FDL communication using program blocks of Open User
Communication (OUC) see section Configuration, program blocks (Page 29).

Application and functions
1.2 Further functions
SIMATIC CM 1542-5
12 Operating Instructions, 01/2023, C79000-G8976-C290-07
•S7 communication
–PG communication for uploading / downloading of S7 configuration, diagnostics and
routing
–Operator control and monitoring functions (HMI communication)
–Data exchange over S7 connections
•Data record routing / field device parameter assignment
You can use the CM as a router for data records intended for field devices (DP slaves). Data
records from devices that are not connected directly to PROFIBUS and therefore have no
direct access to the DP slaves are forwarded to the DP slaves by the CM.
The services of the CM 1542-5 listed above can be used independently at the same time.
Note
Requirement for FDL, data record routing, loading of configuration/diagnostics data
For the functions FDL, data record routing and loading configuration and diagnostics data the
CM must either be operated in the mode DP master mode or as a DP slave with the option
"Test, Commissioning and Routing" enabled.
1.2 Further functions
Enabling /disabling DP slave - in the standard system
DP slaves can be activated and deactivated by the user program using system function
D_ACT_DP.
Diagnostics requests
As a DP master (class 1), the CM 1542-5 supports diagnostics requests of a DP master (class
2).
Getting the bus topology in a DP master system
The CM 1542-5 operating as DP master supports the measurement of the PROFIBUS bus
topology in a DP master system using a diagnostics repeater (DP slave).
System function DP_TOPOL in the user program can instruct diagnostics repeaters to measure
the PROFIBUS BUS topology in a DP master system.

Application and functions
1.3 Configuration limits and performance data
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 13
Time-of-day synchronization - time master or time slave
The CM 1542-5 can be enabled for time-of-day synchronization. As an alternative, the CM can
be configured as time master or time slave on PROFIBUS.
•Time master: The CM is synchronized using the time of day in the S7-1500 station and
outputs the time of day on PROFIBUS. The output interval can be set.
•Time slave: The CM receives time-of-day frames on PROFIBUS and outputs the time within
the S7-1500 station. The output interval within the S7-1500 station is set permanently to
10 seconds.
Note
Recommendation for setting the time
It is advisable to set the time
-of-day master so that time-of-day frames are sent at intervals of
approximately 10 seconds. This achieves as small a deviation as possible between the internal
time and the absolute time.
Web diagnostics
With the aid of Web diagnostics of the CPU, you read the diagnostics data from an S7 station
via the Web browser on the PG/PC.
In terms of the CM, the Web pages provide the following information:
•Module and status information
•Special information on the DP master system (status of the DP slaves)
1.3 Configuration limits and performance data
1.3.1 Configuration limits - number of CMs
When using the CM type described here, the following limits apply:
•The number of CMs that can be operated in a rack depends on the CPU type being used.
Refer to the information in the system manual (hardware configuration) Preface (Page 3)
> Documentation guide.

Application and functions
1.3 Configuration limits and performance data
SIMATIC CM 1542-5
14 Operating Instructions, 01/2023, C79000-G8976-C290-07
1.3.2 Transmission speeds supported
The transmission speed is set in STEP 7.
Note
Remember the cable length
For the selected transmission speed, the permitted cable length must be kept to.
For this refer to the information in the PROFIBUS function manual:
Link: (https://support.industry.siemens.com/cs/ww/en/view/59193579)
1.3.3 Characteristic data of the DP interface
Characteristic data of DP mode
No special program blocks are required for DP mode. The interfacing to the distributed I/O is
by direct I/O access or using program blocks (SFCs/SFBs) of the CPU.
Table 1- 1 Characteristic data of DP mode
Characteristic
Explanation / values
Max. number of operable DP slaves
125 *
Max. size of the input area of all DP slaves
8 KByte
Max. size of the output area of all DP slaves
8 KByte
Maximum number of inputs per DP slave
244 Byte
Maximum number of outputs per DP slave
244 Byte
Max. size of the consistent area for a module
128 Byte
* When using DP slaves with extensive configuration data e.g. SINAMICS devices, the number of DP
slaves that can be operated on the CM sinks.
Diagnostics requests
As a DP master (class 1), the CM 1542-5 supports diagnostics requests of a DP master (class
2).
DP startup behavior
Note
Increasing the default value for startup parameters
- configuration of the CPU
In some situations, it is necessary to increase the default value for the startup parameter
"Parameter assignment time for the distributed I/O" in the configuration of the CPU:
•
A large number of modules (DP slaves) is configured.
•
When a high value is configured for the constant bus cycle time in the network properties
of the PROFIBUS DP line.

Application and functions
1.3 Configuration limits and performance data
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 15
1.3.4 Characteristic data of FDL communication
Characteristic data FDL
The characteristic data is important when operating FDL connections (specified, free layer 2
(SDA and SDN), broadcast, multicast):
Table 1- 2 Characteristic data FDL
Characteristic
Explanation / values
Total number of S7 connections via
PROFIBUS and FDL connections together
Operable in total: Max. 48
•Of which, FDL connections • Max. 30
•Size of the transferable data area for FDL
connections
•1...240 bytes max. per specified FDL connection (for sending and
receiving)
•Free layer 2, broadcast and multicast:
Up to 236 bytes of payload can be transferred per job. The job header
occupies an additional 4 bytes.
Note
Connection resources of the CPU
Depending on the CPU type, different numbers of connection resources are available. The
number of connection resources is the decisive factor for the number of configurable
connections. For this reason, lower values than specified here can result.
You will
find detailed information on the topic of connection resources in the
"Communication" function manual:
Link: (http://support.automation.siemens.com/WW/view/en/59192925)
1.3.5 Characteristics of S7 communication
Characteristics of S7 communication
The following information is important when operating S7 connections:
Table 1- 3 Characteristics of S7 connections
Characteristic
Explanation / values
Total number of S7 connections via
PROFIBUS and FDL connections
together
Operable in total: Max. 48
•Of which, S7 connections via
PROFIBUS
•Max. 48
The value depends on the S7-1500 CPU being used.

Application and functions
1.4 Requirements for use
SIMATIC CM 1542-5
16 Operating Instructions, 01/2023, C79000-G8976-C290-07
Note
PG or HMI functions or data record routing
If PG or HMI functions or data record routing are used, a suitable number of S7 connections
must be reserved during configuration!
Help provided by STEP 7
The number of connections on PROFIBUS shown in the table above can vary due to other
influencing factors. The STEP 7 configuration tool displays warnings and help messages as
soon as limit values are exceeded.
1.3.6 Performance data / operation
Measured values of transfer or reaction times
Measured values of transfer and reaction times in Ethernet, PROFIBUS and PROFINET
networks for a series of configurations can be found on the Internet:
Link: (https://support.industry.siemens.com/cs/ww/en/view/25209605)
1.4 Requirements for use
1.4.1 Usable CPUs
The following CPUs can be used as local CPU of the communications module:
•Compatible CPUs
All CPUs that can be configured in STEP 7 as of firmware version V2.1 from the following
series:
–Standard CPUs (CPU 15xx)
–Compact CPUs (CPU 15xxC)
–Technology CPUs (CPU 15xxT / TF)
–Fail-safe CPUs (CPU 15xxF)
The following CPUs cannot be used:
•Non-compatible CPUs
–H-CPU (CPU 1517H / HF)
–R-CPUs (CPU 151xR)

Application and functions
1.4 Requirements for use
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 17
Note
Keep the firmware ver
sion of the CPUs and communications modules up to date
To avoid possible problems when using newer CPUs together with older communications
modules, you should keep the firmware of both your communications modules and your
CPUs up to date.
Check regularly f
or security updates for the firmware and use them.
Information regarding product news and new firmware versions of the communications
module is available at the following address:
Link: (https://support.industry.siemens.com/cs/ww/en/ps/15671/dl)
1.4.2 Project engineering
Configuration
To configure the CM, the following configuration tool is required:
STEP 7 version
CM (6GK7542-5DX00-0XE0)
CM (6GK7542-5DX10-0XE0)
STEP 7 Professional V17 The functionality of the CM with
firmware version V2.0.24 can be
configured.
The CM is configurable, but with
the functionality of the CM
(6GK7542-5DX00-0XE0) with
firmware version V2.0.24.
STEP 7 Professional V18
The functionality of the CM with
firmware version V2.0.24 can be
configured.
The functionality of the CM with
firmware version V3.0 can be
configured.
Downloading configuration data
When the configuration data is loaded on the CPU, the CM is supplied with the relevant
configuration data. The configuration data can be downloaded to the CPU via PROFIBUS or
any PROFINET interface of the S7-1500 station.
1.4.3 Program blocks
Program blocks
For the use of the program blocks for the CM, STEP 7 in the following version is required:
STEP 7 version
CM (6GK7542-5DX00-0XE0)
CM (6GK7542-5DX10-0XE0)
STEP 7 Professional V17 Using the program blocks for the
CM with firmware version V2.0.24
Using the program blocks for the
CM with firmware version V2.0.24
STEP 7 Professional V18 Using the program blocks for the
CM with firmware version V2.0.24
Using the program blocks for the
CM with firmware version V3.0

Application and functions
1.5 LEDs
SIMATIC CM 1542-5
18 Operating Instructions, 01/2023, C79000-G8976-C290-07
Use of FDL
The following minimum firmware versions are required for using the FDL functionality:
•CM: V2.0.20
•CPU: V2.0
1.5 LEDs
The status and error displays of the CM 1542-5 are described below.
You can find additional information on "Interrupts" in the STEP 7 online help.
You can find additional information on "Diagnostics" and "System alarms" in the function
manual on the Internet:
Link: (https://support.industry.siemens.com/cs/ww/en/view/59192926)
LED display
The following figure shows the LEDs of the CM 1542-5.
①
RUN/STOP LED
②
ERROR LED
③
MAINT LED
Figure 1-1 LED display of the CM 1542-5 (without front cover)

Application and functions
1.6 PROFIBUS interface
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07 19
Meaning of the LED displays
The CM 1542-5 has 3 LEDs to display the current operating status and the diagnostics status
and these have the following meanings:
•
RUN/STOP LED
(one-color LED: green)
•
ERROR LED
(one-color LED: red)
•
MAINT LED
(one-color LED: yellow)
The following table shows the meaning of the various combinations of colors of the
RUN/STOP, ERROR and MAINT LEDs.
Table 1- 4 Meaning of the LEDs
RUN/STOP LED
ERROR LED
MAINT LED
Meaning
LED off
LED off
LED off
No supply voltage on the CM or supply
voltage too low.
LED lit green
LED lit red
LED lit yellow
LED test during startup
LED lit green
LED lit red
LED off
Startup (booting the CM)
LED lit green
LED off
LED off
CM is in RUN mode.
No disruptions
LED flashing
green
LED off LED off
No CM configuration exists
Loading firmware
LED lit green
LED flashing red
LED off
A diagnostics event has occurred.
LED lit green
LED off
LED lit yellow
Maintenance is demanded.
LED lit green LED off
LED flashing
yellow
Maintenance is required.
LED flashing
green
LED flashing red LED flashing
yellow
Module fault
1.6 PROFIBUS interface
9-pin D-sub female connector (PROFIBUS)
The PROFIBUS connector is located behind the cover of the housing. The interface is a 9-pin
D-sub female connector operating according to the RS-485 standard.
You also have the option of connecting to optical PROFIBUS networks via an Optical Bus
Terminal OBT or an Optical Link Module OLM.
You will find the pin assignment of the D-sub socket in section PROFIBUS interface terminal
assignment (Page 57).

Application and functions
1.6 PROFIBUS interface
SIMATIC CM 1542-5
20 Operating Instructions, 01/2023, C79000-G8976-C290-07