Dräger ISA100 Technical Manual

Wireless communication

ISA100 Wireless

Technical Manual

Wireless communication

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2 Technical Manual | Wireless communication

Contents

Wireless communicationISA100 Wireless

Contents

1 Introduction .............................................................................................. 5

1.1 Target group ................................................................................... 5

1.2 General safety statements.............................................................. 5

1.3 Meaning of the warning notes......................................................... 5

1.4 Typographical conventions............................................................. 5

1.5 Brand names .................................................................................. 6

2 Wireless data transmission in industrial settings................................. 7

3 ISA100 Wireless

basics ....................................................................... 9

3.1 Network components and participants............................................ 10

3.1.1 System manager .............................................................. 11

3.1.2 Backbone.......................................................................... 11

3.1.3 Access points (AP) ........................................................... 11

3.1.4 Field devices..................................................................... 12

3.1.5 Hop points ........................................................................ 13

3.2 Network topologies ......................................................................... 14

3.2.1 Star topology .................................................................... 14

3.2.2 Mesh topology .................................................................. 15

3.2.3 Comparison of star topology and mesh topology ............. 16

3.3 Network performance and network configuration ........................... 16

3.3.1 Signal quality .................................................................... 16

3.3.2 Network coverage............................................................. 18

3.3.3 Sub-networks.................................................................... 19

3.3.4 Sky mesh.......................................................................... 20

3.3.5 Network configuration with retrofitted field devices .......... 20

3.3.6 Network configuration for small networks......................... 21

3.3.7 Network configuration with long backbone lines............... 22

3.3.8 Network configuration with a 4–20 mA control unit .......... 24

4 ISA100 Wireless

data transmission basics........................................ 25

4.1 Frequency band and bandwidth ..................................................... 25

4.2 Data integrity................................................................................... 26

4.2.1 Frequency hopping........................................................... 26

4.2.2 Hopping patterns .............................................................. 26

4.2.3 Standard hopping pattern................................................. 27

4.2.4 Duo-Cast .......................................................................... 28

4.2.5 Time-Division-Multiple-Access (TDMA)............................ 28

4.2.6 Clear channel assessment (CCA) .................................... 28

4.2.7 Automatic-Repeat-reQuest (ARQ).................................... 28

4.2.8 Blacklisting........................................................................ 29

4.2.9 Adaptive hopping.............................................................. 29

4.2.10 Path diversity .................................................................... 29

4.2.11 Types of routing ................................................................30

4.3 Data structure ................................................................................. 30

4.3.1 Data fields......................................................................... 31

4.3.2 User application process (UAP) ....................................... 32

4.3.3 Object identifiers............................................................... 33

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Contents

4.3.4 Attribute classes ............................................................... 34

4.3.5 Data format (without PROFIsafe

communication).......... 35

4.4 Traffic.............................................................................................. 35

4.4.1 Data query ........................................................................ 36

4.4.2 Sampling rate and stale limit ............................................ 36

4.4.3 Network and energy management with ISA100 wireless

communication ................................................................. 38

4.4.4 Device performance information....................................... 39

5 Transmission basics for PROFIsafe

5.1 Black channel principle ................................................................... 40

5.2 Data integrity for PROFIsafe

5.2.1 PROFIsafe

network constraints...................................... 42

communication ......................... 40

communication ............................... 41

5.3 Data structure ................................................................................. 42

5.3.1 Data fields......................................................................... 42

5.3.2 Data format for PROFIsafe

5.4 Traffic for PROFIsafe

communication .......................................... 43

communication ................... 43

6 Network integration (provisioning) of gas warning devices................ 45

6.1 Network integration parameters...................................................... 45

6.1.1 Modbus parameters.......................................................... 45

6.1.2 PROFIsafe

traffic............................................................ 45

6.2 Out Of Band Provisioning (OOB, Yokogawa gateway only)........... 46

6.3 Over the air provisioning (OTA)...................................................... 48

7 Troubleshooting....................................................................................... 49

7.1 Errors during network integration.................................................... 49

7.2 Errors during operation ................................................................... 49

7.2.1 Status byte of a transmitted value .................................... 49

7.2.2 DIAG_STATUS attribute byte........................................... 51

8 Recommended network components..................................................... 53

8.1 Network components recommended without restrictions ............... 53

8.1.1 System manager .............................................................. 53

8.1.2 Access points ................................................................... 53

8.1.3 Other components............................................................ 53

8.2 Network components recommended with restrictions .................... 53

8.2.1 System manager .............................................................. 53

9 Glossary.................................................................................................... 54

9.1 Glossary on parameter and object names...................................... 55

4 Technical Manual | Wireless communication

1 Introduction

This document supplements the instructions for use for gas warning devices:

– Dräger Polytron

– GasSecure GS01 / GasSecure GS01-EA

– Polytron Repeater ISA100

– Polytron 6700 IR WL

This document contains additional information on the ISA100 Wireless

1.1 Target group

This document is intended for technicians with training in PLC programming, trained electricians or persons who have received instruction from a trained electrician. These persons must also be familiar with the applicable standards.

1.2 General safety statements

Before using this product, carefully read the associated instructions for use. This document does not replace the instructions for use.

6100 EC WL

Introduction

interface.

1.3 Meaning of the warning notes

The following warning notes are used in this document to notify users of possible dangers. The meanings of the warning notes are defined as follows:

Alert icon Signal word Consequences in case of nonob-

servance

WARNING Indicates a potentially hazardous situation

which, if not avoided, could result in death or serious injury.

CAUTION Indicates a potentially hazardous situation

which, if not avoided, could result in injury. It may also be used to alert against unsafe practices.

NOTICE Indicates a potentially hazardous situation

which, if not avoided, could result in damage to the product or environment.

1.4 Typographical conventions

Text Text marked in bold denotes labeling on the device and on-screen

messages.

► This triangle labels possible methods of avoiding the hazards men-

tioned in warning notices.

> The greater-than sign denotes the navigational path in a menu.

This symbol denotes information that make using the product easier.

Technical Manual | Wireless communication 5

Introduction

1.5 Brand names

–HART® is a registered trademark of the HART Communication Foundation.

–PROFIBUS

e. V.

– FOUNDATION

– ISA100 Wireless

Automation (ISA).

– Bluetooth

– WirelessHART

Communication Foundation.

–PROFIsafe

is a registered trademark of the PROFIBUS Nutzerorganisation

is a registered trademark of Bluetooth SIG, Inc.

is a registered trademark of Siemens Aktiengesellschaft.

is a registered trademark of the Fieldbus Foundation.

is a registered trademark of the International Society of

(WHART) is a registered trademark of the HART

6 Technical Manual | Wireless communication

Wireless data transmission in industrial settings

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2 Wireless data transmission in industrial settings

There are a number of different protocols and types of network for wireless data transmission, which will be described in this manual in conjunction with Dräger products. The following diagram shows the application areas for various protocols. Other protocols (WPAN, for example) are not considered in this context.

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Fig. 1 Wireless data transmission protocols

1WFAN 2WLAN 3

Bluetooth

or infrared

WLAN and WFAN

In a WFAN (Wireless Field (or Factory) Area Network), industrial field devices communicate with one another or with a control center. The control center controls and monitors the field devices. When communicating via WFAN, protocols such as ISA100 Wireless

and WirelessHART® (WHART) are used.

WLAN (Wireless Local Area Network) is a local, usually private wireless network. The WLAN infrastructure of an industrial plant is used for mobile end devices and video transmission (stationary cameras).

Technical Manual | Wireless communication 7

Wireless data transmission in industrial settings

Main application areas

There are 3 main areas of application for wireless networks:

– Plant safety

Transmitters monitor safety-critical areas and send wireless measured values. ISA100 Wireless

allows for SIL 2-compliant failsafe communication through

the transport of PROFIsafe

– Monitoring field devices

The status of field devices is monitored (e.g. temperature, sensor status of a gas warning device).

– Process monitoring and process control

Wireless data transmission allows for detailed process monitoring and process control without expensive cable routing costs. These areas of application must be able to tolerate latencies of 100 ms.

Advantages of a wireless network

Wireless networks offer many advantages compared to wired networks.

– Wireless networks can be made operational more quickly and installing the

infrastructure creates less costs.

– Wireless networks can be expanded with greater ease and at less cost. Adding

new field devices and putting them into operation, as well as removing them, is easier.

– The parameters of field devices as well as diagnostics and maintenance can be

configured centrally.

– Errors do not occur when wiring field devices (e.g. cable break, wiring problems

in the field device).

– Wireless networks can be employed in places a wired network would be

impossible, expensive, or difficult to implement (e.g. on rotating platforms).

– Temporary installations that are dismantled after a certain time also profit from

wireless networking. Temporary installations no longer need arduous and expensive cabling.

messages.

Furthermore, a wired network’s infrastructure can be expanded wirelessly (creating redundancy).

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3 ISA100 WirelessTM basics

ISA100.11a is a wireless networking protocol internationally recognized as IEC Standard 62734 and developed by the International Society of Automation (ISA). It is based on the ISO/OSI reference model and allows for reliable, secure data transmission for control- and regulation-related applications, process monitoring and alerts.

ISA100 Wireless data transmission even over long distances with low power consumption.

As with most fieldbus systems, a ISA100 Wireless any field devices required due to standardization. All field devices in the network can interact with one another independent of manufacturer.

ISA100 Wireless system management, gateway requirements and security specifications.

Failsafe communication

ISA100 Wireless between controller and field device. This secure data transfer method is performed via tunneling. Tunneling facilitates the use of different communication protocols via the ISA100 Wireless PROFIsafe outside the ISA100 Wireless

is comparable to a fieldbus system in that it allows for reliable

defines basic functions and requirements for field devices,

allows for failsafe communication (e.g. SIL 2-compliant)

communication protocol. This communication protocol is transmitted

infrastructure. Failsafe communication is done via the

infrastructure via PROFINET.

ISA100 WirelessTM basics

network can be expanded with

Advantages of ISA100 Wireless

There are different wireless network protocols. Among others, the ISA100 Wireless

– Transfer of other communication standards (e.g. PROFIsafe

protocol has the following advantages over other protocols:

, HART®)

– Bandwidth for safety-relevant data can be reserved. This reserved bandwidth

ensures the rapid transmission of safety-relevant data at any time to the control center. The transmission of safety-relevant data is not affected by other data traffic.

– Response times of a ISA100 Wireless

network are variable and shorter than

those of other protocols.

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ISA100 WirelessTM basics

3.1 Network components and participants

Fig. 2 Example topology of a wireless network

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1 Control center 2 Control unit for wired field devices 3 Control unit 4 System manager 5 Access point in the function as a backbone router 6 Access point 7 Access point in the function as a field device access point 8Hop point 9 Retrofitted field device 10 I/O field device 11 GasSecure GS01 12

Dräger Polytron

6100 EC WL 13 Backbone 14 Ethernet or fiber-optics 15 Wireless data transmission from an access point to the backbone 16 Wireless data transmission between field devices and to the backbone 17 Wired analog or digital communication 18

Wired Modbus communication or PROFIsafe

communication via PROFI-

BUS/PROFINET

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3.1.1 System manager

The system manager monitors and manages the following system functions, among others:

– Security management

– System performance, system latencies, redundancy

– System time

– Field device management (e.g. address allocation and routing tables)

Wireless gateway and system manager are the same thing for the purposes of this manual. In detailed descriptions, system managers and gateways must be considered separately from one another.

Controllers are connected to the system manager (e.g. Dräger REGARD with Modbus Master module). Control units process the system manager’s data and trigger alerts or countermeasures.

If PROFIsafe F-host (failsafe host) must be used as a controller , which communicates with Fslaves (FailSafe field devices). In this case, the system manager only forwards the messages and does not interfere with PROFIsafe

is used for communication purposes (e.g. for SIL 2 applications), an

ISA100 WirelessTM basics

communication.

7000

3.1.2 Backbone

The backbone is the wired part of the network, which connects the backbone router (BBR) to the system manager. The connection is established via fiber-optic cable (FOC) or Ethernet.

3.1.3 Access points (AP)

An access point is the transition from the wireless to the wired parts of the network. Access points transmit the information from their end devices via cable to the system manager. APs can be compared to the base station of a mobile landline phone. In both cases, a wireless network is established for a multitude of mobile end devices.

An AP performs different roles depending on the position in which it is located in the network.

3.1.3.1 Backbone router (BBR)

If an access point is wired directly to the backbone, the access point is referred to as the backbone router. Several backbone routers can be connected to the backbone.

Field devices and field device access points communicate wirelessly with the backbone router via the sub-network, which is established by the backbone router.

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ISA100 WirelessTM basics

Additional access points can be wired to the backbone router.

Risk of confusion Backbone routers are connected to the backbone via cables. Repeaters or field devices with routing functionalities are often also referred to as routers. However, these "routers" are not connected to the backbone via cables and only forward the signals.

Backbone routers as part of the system manager

Backbone routers can also be part of the system manager.

3.1.3.2 Field device access points (FDAP)

Field device access points are access points that communicate wirelessly with the backbone. Communication to the backbone is done either via access points or directly over the backbone router.

Dräger-approved devices are listed in the appendix.

3.1.4 Field devices

Field devices may also be called terminal devices or clients. They log on to the AP and exchange information. Field devices are also called I/O devices because they receive (input) and send (output) data.

There are field devices that communicate with the control center via cable in addition to communicating wirelessly. These field devices are retrofitted with an ISA100 Wireless

antenna. They additionally communicate via wire with another

interface (a 4–20 mA interface, for example).

Field devices can be mobile field devices (tablets, smartphones, laptops), stationary field devices or slow-moving stationary field devices. Mobile field devices often communicate with an additional system manager or gateway via a different protocol (non-ISA100 Wireless

Due to their being integral elements of the network infrastructure, access points or field device access points are not called field devices.

3.1.4.1 Routing functionalities

Some field devices can also act as a router in addition to their normal functionality. Field devices with this function activated create hop points in the network.

These devices are often connected to a power line due to the extra energy requirements involved in router operation.

Field devices with routing functionalities are also available without measuring functions. They are then only integrated into the network as routers. The Polytron Repeater ISA100 is a router without measuring function.

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3.1.4.2 Power supply

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ISA100 WirelessTM basics

Power is supplied to field devices via batteries or the power grid. ISA100 Wireless

allows for every type of power supply.

If battery operation is not possible, field devices are connected to an external power supply. An external power supply may be necessary if the routing functionality is active and there is a lot of wireless communication.

When operating in explosion-hazard areas, an upstream safety barrier must be installed for external power supplies.

3.1.5 Hop points

Routers or field devices with a router function form a hop point in the sub-network.

Hop points expand a network and ensure redundant transmission routes. Signals are forwarded without processing and no separate sub-network is established.

Data transmissions via hop points to the system manager are slower than direct data transmissions to access points. Latencies (wait times) at the hop points can delay communication.

The communication paths via hop points are prevented ex-factory for some system managers. But, the function can be activated.

Restrictions for installations with short response times

Series-connected hop points can delay the response time. If response times are a critical factor, there must be a limited number of hops (wireless interfaces) from the field device to the access point. Fig. 3 shows a sub-network with only one (1) or two (2) hops allowed.

Fig. 3 Hop points in a sub-network

1 First hop point after the sub-network access point

One further hop point is possible.

2 Second hop point after the sub-network access point

Another hop point could cause too much of a delay in the response time.

System managers from Yokogawa support a maximum of 4 hops (wireless interfaces) between a field device and the backbone router (as at September 2020).

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ISA100 WirelessTM basics

1 2

3.1.5.1 Routers

Routers are also called repeaters. Routers increase the size of the network and cancel out weak spots. They form a hop point in the sub-network. Incoming data is forwarded without processing.

Routers do not establish their own sub-networks.

3.2 Network topologies

There are 3 network topologies for ISA100 networks.

– Star topology

– Mesh topology

– Partial mesh topology

3.2.1 Star topology

In a star topology, field devices communicate with one or more access points. The field devices can only exchange information via access points, not directly with one another. Multiple access points are often employed to make the network more failsafe.

Fig. 4 Star topology and communication channels

1 Primary communication channel 2 Secondary communication channel

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14 Technical Manual | Wireless communication

3.2.2 Mesh topology

In a mesh topology, all network participants that are within range communicate with one another. Field devices, routers and access points can be network participants.

In a mesh network, the data transmission is redundant. If communication over a field device or a repeater is interrupted, the data is transmitted via other network participants.

Fig. 5 Mesh topology

ISA100 WirelessTM basics

4093640937

3.2.2.1 Partial mesh topology

The mesh topology and star topology can be mixed. This combination is called a partial mesh topology or star-mesh topology. In this topology, a core network, in which all network participants are interconnected, is expanded with network participants that are no longer connected with all network participants.

Fig. 6 Partial mesh topology

1 Preferred communication channel 2 Redundant communication channel

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ISA100 WirelessTM basics

3.2.3 Comparison of star topology and mesh topology

Network cards are best compared by using the most important criteria for networks: Reliability and latency.

Reliability

In a mesh network, network participants exchange information with each other (IoT approach). If one network participant fails, communication is still possible. If a network participant fails in a star topology, communication can fail.

Latencies

The latency of star topologies is usually less than that of meshed ones due to the field devices being directly connected to an access point.

3.3 Network performance and network configuration

The wireless connection between field devices and the access point depends greatly on the surroundings. The connection is best when there is an unobstructed line of sight between the two. Oftentimes, however, there is no line of sight (due to intervening pipes or walls, for example). If the line of sight is obstructed, routers or the reflective properties of the obstacles themselves are used.

3.3.1 Signal quality

The signal quality of wireless transmissions depends on the signal strength (RSSI) and the signal integrity (PER or TxFail rate). The RSQI range is another indicator of signal quality.

PER or TxFail rate

This value represents the error rate during data transmission from the field device to the backbone. This value is displayed as a percentage. The lower the value, the better the integrity of data transmission. High values show poor data transmission integrity. Poor data integrity can be caused by unfavorable communication paths or interferences (other wireless technologies or obstacles, for example).

The expression and the limit values of this error rate depend on the manufacturer of the system manager. The error rate can be expressed either as PER (packet error rate) or as a TxFail rate.

RSSI

RSSI (received signal strength indication) shows the received signal strength between the field device and the access point. RSSI is expressed in dBm (decibelmilliwatts). The received signal strength is always shown as a negative number. The closer the value is to zero, the better the wireless connection.

RSQI

RSQI (received signal qualitiy indication) shows the received signal strength between the field device and the access point. RSQI is a calculated value. Higher values indicate better data transmission than lower values. Four quality classes are defined in the standard ISA-100.11a (see table below).

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ISA100 WirelessTM basics

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Signal quality values and their meaning

The interpretation of the value ranges can be adjusted in some system managers. The following table provides an example of the ranges for the purpose of orientation.

Indicator Value range Meaning

PER / TxFail rate 0 to 15 % Good

15 to 100 % High

RSSI -75 to -25 dBm Good

-85 to -75 dBm Acceptable

-100 to -85 dBm Poor

RSQI 196 to 255 Excellent

128 to 195 Good 64 to 127 Acceptable 0 to 63 Poor

Fresnel zone

Signal quality can be disrupted by obstacles even if transmitter and receiver have line of sight. Disruption due to obstacles occurs when obstacles are located in the Fresnel zone. The Fresnel zone is an elliptical area formed around the line of sight, whose diameter increases with the transmission range. It is therefore recommended to install antennas as high up as possible to ensure longer distances are covered.

Fig. 7 Line of sight between field device and access point with an elliptical

Fresnel zone

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