
S7-1500 - PROFIBUS
CM 1542-5
Guide to the documentation
Product overview, functions
Installation, connecting up,
commissioning, operation
Configuration, programming

Siemens AG
Division Process Industries and Drives
Postfach 48 48
90026 NÜRNBERG
GERMANY
11/2018 Subject to change
Copyright © Siemens AG 2013 - 2018.
All rights reserved
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indicates that death or severe personal injury may result if proper precautions are not taken.
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editions.

CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
3
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.
In this document, the term "CM" (communications module) is used instead of the full
product name "CM 1542-5".
●
The name STEP 7 is used to mean the STEP 7 Professional configuration tool.
● New ATEX/IECEx approval
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
)
Sources of information and other documentation
See section Guide to the documentation (Page 9).

Preface
CM 1542-5
4 Operating Instructions, 11/2018, C79000-G8976-C290-04
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
The firmware is signed and encrypted. This ensures that only firmware created by Siemens
can be downloaded to the device.
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: (http://www.siemens.com/industrialsecurity
)
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.

Preface
CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
5
● Restrict physical access to the device to qualified personnel.
● Configure a protection level of the CPU.
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.
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
)
Explanations of many of the specialist terms used in this documentation can be found in the
SIMATIC NET glossary.
You will find the SIMATIC NET glossary on the Internet at the following address:
Link: (https://support.industry.siemens.com/cs/ww/en/view/50305045
)

Preface
CM 1542-5
6 Operating Instructions, 11/2018, C79000-G8976-C290-04

CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
7
Preface ................................................................................................................................................... 3
1 Guide to the documentation .................................................................................................................... 9
2 Product overview, functions................................................................................................................... 11
2.1 Product data ............................................................................................................................ 11
2.2 Application .............................................................................................................................. 12
2.3 Further functions ..................................................................................................................... 13
2.4 Configuration limits and performance data ............................................................................. 14
2.4.1 Configuration limits - number of CMs ..................................................................................... 14
2.4.2 Transmission speeds supported ............................................................................................. 15
2.4.3 Characteristic data of the DP interface ................................................................................... 15
2.4.4 Characteristic data of FDL communication ............................................................................. 16
2.4.5 Characteristics of S7 communication ..................................................................................... 17
2.4.6 Performance data / operation ................................................................................................. 17
2.5 Requirements for use.............................................................................................................. 18
2.5.1 Project engineering ................................................................................................................. 18
2.5.2 Programming .......................................................................................................................... 18
2.6 LEDs ....................................................................................................................................... 19
2.7 PROFIBUS interface ............................................................................................................... 20
3 Installation, connecting up, commissioning, operation ........................................................................... 21
3.1 Important notes on using the device ....................................................................................... 21
3.1.1 Notes on use in hazardous areas ........................................................................................... 21
3.1.2 Notes on use in hazardous areas according to ATEX / IECEx .............................................. 22
3.1.3 Notes on use in hazardous areas according to UL HazLoc ................................................... 22
3.1.4 Notes on use in hazardous areas according to FM ................................................................ 23
3.2 Installing and commissioning the CM 1542-5 ......................................................................... 23
3.3 Pin assignment PROFIBUS .................................................................................................... 24
3.4 Mode of the CPU - effect on the CM ....................................................................................... 25
4 Configuration, programming .................................................................................................................. 27
4.1 Configuration in STEP 7 ......................................................................................................... 27
4.2 Program blocks for communication and distributed I/O .......................................................... 27
4.3 Program blocks for FDL .......................................................................................................... 28
5 Diagnostics and upkeep ........................................................................................................................ 35
5.1 Diagnostics options ................................................................................................................. 35
5.2 DP slave diagnostics............................................................................................................... 36
5.3 Standard diagnostics .............................................................................................................. 37

Table of contents
CM 1542-5
8 Operating Instructions, 11/2018, C79000-G8976-C290-04
5.4 Device-specific diagnostics in DP-V1 .................................................................................... 39
5.5 DP diagnostics frames when the CPU is in STOP ................................................................ 42
5.6 Replacing a module without a programming device .............................................................. 42
6 Technical specifications ........................................................................................................................ 43
7 Approvals ............................................................................................................................................. 45
Index .................................................................................................................................................... 51

CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
9
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
CM 1542-5 and are available in the Internet.
Table 1- 1 Documentation for the CM 1542-5
System description
System manual: S7-1500 Automation System
(
https://support.industry.siemens.com/cs/ww/e
n/view/59191792)
• Application planning
• Installation
• Connecting
• Commissioning
Module properties Device manual: Power supplies
(
https://support.industry.siemens.com/cs/ww/e
• Connecting
• Parameter assignment/
addressing
• Interrupts, error messages,
diagnostics and system
alarms
• Technical specifications
• Dimensional drawing
Device manual: Signal modules
(
https://support.industry.siemens.com/cs/ww/e
n/ps/13743/man)
System diagnostics
Function manual: System diagnostics
(
https://support.industry.siemens.com/cs/ww/e
n/view/59192926)
• Overview
• Diagnostics evaluation for
hardware/software
Communication Function manual: Communication
(
https://support.industry.siemens.com/cs/ww/e
• Overview
Function manual PROFINET with STEP 7
(
https://support.industry.siemens.com/cs/ww/e
n/view/49948856)
• PROFINET basics
• PROFINET functions
• PROFINET diagnostics

Guide to the documentation
CM 1542-5
10 Operating Instructions, 11/2018, C79000-G8976-C290-04
Function manual PROFIBUS with STEP 7
(
https://support.industry.siemens.com/cs/ww/e
n/view/59193579)
• PROFIBUS basics
• PROFIBUS functions
• PROFIBUS diagnostics
Function manual: Web Server
(
https://support.industry.siemens.com/cs/ww/e
n/view/59193560)
• Function
• Operation
Interference-free
installation of
control systems
Function Manual: Interference-free installation
of control systems
(
https://support.industry.siemens.com/cs/ww/e
n/view/59193566)
• Basics
• Electromagnetic compatibil-
ity
• Lightning protection
• Housing selection
Memory concept Function manual: Structure and Use of the
CPU Memory
(https://support.industry.siemens.com/cs/ww/e
n/view/59193101)
• Design
• Principle of operation
• Use
Cycle and response times
Function manual: Cycle and Response Times
(
https://support.industry.siemens.com/cs/ww/e
• Basics
• Calculations
Analog value
processing
Function manual: Analog value processing
(
https://support.industry.siemens.com/cs/ww/e
• Wiring options
• Tables of measured values
All current manuals for SIMATIC products are available for download free of charge from the
Internet:
Link: (http://www.siemens.com/automation/service&support
)
CP/CM documentation in the SIMATIC NET Manual Collection (article number A5E00069051)
The "SIMATIC NET Manual Collection" DVD contains the device manuals and descriptions
of all SIMATIC NET products current at the time it was created. It is updated at regular
intervals.
Version History / current downloads for the SIMATIC NET S7-CPs/CMs
The "Version History/Current Downloads for SIMATIC NET S7 CPs (PROFIBUS)" provides
information on all CPs available up to now for SIMATIC S7 (PROFIBUS). You will find the
document on the Internet:
Link: (https://support.industry.siemens.com/cs/ww/en/view/67225941
)

CM 1542-5
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Product data
Article number, validity and product names
This description contains information on the following product:
CM 1542-5
Article number 6GK7 542-5DX00-0XE0
Hardware product version 1
Firmware version V2.0.15
Communications module CM 1542-5 for connection of S7-1500 to PROFIBUS DP
PROFIBUS interface: 1 x 9-pin D-sub female connector (RS-485)
Figure 2-1 CM 1542-5 with closed (left) and open (right) front cover

Product overview, functions
2.2 Application
CM 1542-5
12 Operating Instructions, 11/2018, C79000-G8976-C290-04
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 by the user program using system function
DPSYNC_FR.
●
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.
The CM handles the FDL communication using program blocks of Open User
Communication (OUC) see section Configuration, programming (Page 27).

Product overview, functions
2.3 Further functions
CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
13
●
– 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.
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.
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.

Product overview, functions
2.4 Configuration limits and performance data
CM 1542-5
14 Operating Instructions, 11/2018, C79000-G8976-C290-04
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 interval
s of
approximately 10 seconds. This achieves as small a deviation as possible between the
internal time and the absolute time.
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)
Configuration limits and performance data
2.4.1
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), see Guide to the
documentation (Page 9).

Product overview, functions
2.4 Configuration limits and performance data
CM 1542-5
Operating Instructions, 11/2018, C79000-G8976-C290-04
15
Transmission speeds supported
The transmission speed is set in STEP 7.
Note
Remember the cable length
For the selected transmission speed, the permitted cable
For this refer to the information in the PROFIBUS function manual:
Link: (https://support.industry.siemens.com/cs/ww/en/view/59193579
)
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 2- 1 Characteristic data of DP mode
Max. number of operable DP slaves
Max. size of the input area of all DP slaves
Max. size of the output area of all DP slaves
Maximum number of inputs per DP slave
Maximum number of outputs per DP slave
Max. size of the consistent area for a module
* 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.
As a DP master (class 1), the CM 1542-5 supports diagnostics requests of a DP master
(class 2).

Product overview, functions
2.4 Configuration limits and performance data
CM 1542-5
16 Operating Instructions, 11/2018, C79000-G8976-C290-04
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.
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 2- 2 Characteristic data FDL
Total number of FDL connections that can
30 max.
Size of the transferable data area for FDL
connections
• 1...240 bytes max. per specified FDL connection (for sending and receiv-
ing):
• Free layer 2 broadcast and multicast:
Up to 236 bytes of user data 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, see Communication
(
http://support.automation.siemens.com/WW/view/en/59192925).