Contents Contents Digital Communication - Foundation Fieldbus Dräger Polytron 8000 Series Introduction ....................Target group ................... General safety statements.............. Meaning of the warning notes............Trade marks..................Basic principles of the Foundation Fieldbus technology..... HSE bus..................Linking devices ................H1 bus basic principles..............
Introduction Introduction This document supplements the instructions for use for gas detectors: – Dräger Polytron 8100 EC – Dräger Polytron 8200 CAT – Dräger Polytron 8310 IR – Dräger Polytron 8700 IR – Dräger Polytron 8720 IR This document contains additional information on fieldbus communication. Target group This document is intended for technicians with training in PLC programming, trained electricians or persons who have received instruction from a trained...
Basic principles of the Foundation Fieldbus technology Basic principles of the Foundation Fieldbus technology Foundation Fieldbus (FF) is an internationally standardized digital communication system. In many areas, it is replacing analog signal transmission using a 4-20-mA interface, which is costly in terms of time and resources. Digital communication offers the following benefits over analog data transmission: –...
Basic principles of the Foundation Fieldbus technology HSE bus Highspeed Ethernet (HSE) is based on Ethernet technology and has a data transfer rate of 100 Mbit/s. Bus access is arbitrary. Devices can access the bus at any time. This may negatively impact on real time processing, thus limiting suitability for applications in automation technology.
Basic principles of the Foundation Fieldbus technology Linking devices Linking devices connect the fast HSE bus and individual H1 buses. They convert the different data rates and telegrams. Linking devices can be bridges or gateways. H1 bus basic principles 2.3.1 H1 bus overview The field devices are connected to the H1 bus.
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Basic principles of the Foundation Fieldbus technology Type A Type B Cable structure Twisted wire pair, One or more twisted shielded wire pairs, overall shielding Core cross-section 0.8 mm² (AWG 18) 0.32 mm² (AWG 22) Loop resistance (DC) 44 Ω/km 112 Ω/km Characteristic impedance at 100 Ω...
Basic principles of the Foundation Fieldbus technology 2.3.5 FISCO model The FISCO model (Fieldbus Intrinsically Safe Concept) was developed by the PTB (Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany) in order to facilitate planning, extending and installing of networks in explosion-hazard areas.
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Basic principles of the Foundation Fieldbus technology 2.4.2 Scheduled traffic Data transmissions that are time-critical are performed by means of scheduled traffic. This includes, for example, controlling of process variables. Scheduled data transmissions follow a strict time schedule that is processed cyclically. This ensures that all data are transmitted in time and that bus access conflicts are prevented.
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Basic principles of the Foundation Fieldbus technology 2.4.4 Sequence control for scheduled and unscheduled traffic The LAS ensures, by means of sequence control, that the scheduled traffic is not interfered with by unscheduled data transmissions (PT Token, TD or PN command etc.).
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Basic principles of the Foundation Fieldbus technology Client/server Diagnostics and modification of field device settings in unscheduled traffic. 2.4.6 Fieldbus message specification (FMS) Data transmission between bus participants is carried out by means of a set of standard telegrams, which are defined by the FMS. The data contained in standard telegrams are allocated to object descriptions.
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Basic principles of the Foundation Fieldbus technology 2.4.7 Function block model An open protocol specification is needed to ensure that devices from different manufacturers can communicate with each other. The protocol specification defines consistent device functions and application interfaces. The general structure of the data transmission is assigned to 3 different blocks.
Basic principles of the Foundation Fieldbus technology Device management 2.5.1 Device description (DD) The device description (DD) of a field device is required for diagnostics, maintenance and integration of the field device into the process control system. The DD is written in a standardized file format and is included in the scope of supply of a field device.
Basic principles of the Foundation Fieldbus technology Communication DTM (COM_DTM) The Communication DTM is a driver that sets up the interface between fieldbus cable and the PC. This interface can for example be a USB-Ethernet converter. The Communication DTM is installed within the FDT framework application. Current and voltage on the H1 bus 2.6.1 Current calculation...
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Basic principles of the Foundation Fieldbus technology 2.6.2 Voltage at the last field device The minimum operational voltage (9 V) must be verified at the field device that is the most distant from the feed unit, since the cable resistance causes a voltage drop.
Installation in the H1 segment - field devices in general Thus the following obtains for the maximum voltage drop over the line: U Lmax 9 V. Example: Feed unit with Ex interface Feed units with Ex interface supply a voltage of 12.8 V..13.4 V. Thus we obtain the maximum voltage drop over the line = US - 9 V = 12.8 V - 9 V = 3.8 V Lmax...
Installation in the H1 segment - field devices in general 3.1.3 Capacitive installation The cable shields are grounded via a capacitor. The capacitors have an electric strength of 1 nF/1500 V. The overall capacity connected to the shielding must not exceed 10 nF.
Installation in the H1 segment - field devices in general 3.2.1 Termination of an MBP interface (on the H1 side) – The linking device at the beginning of the segment has an in-built bus terminator. – In the case of a branched bus segment, the field device that is the most distant from the linking device forms the end of the bus and needs to be terminated.
Installation in the H1 segment - Polytron 8000 UNINITIALIZED (Neither PD tag nor address are set) Assign PD tag Delete PD tag INITIALIZED (Only PD tag is set) Assign adresse Delete adresse SM_OPERATIONAL (PD tag and address are set, function blocks can be executed.) Installation in the H1 segment - Polytron 8000 The installation must be carried out in accordance with the specifications of the FISCO model, the instructions for use and the included control drawings for the...
Installation in the H1 segment - Polytron 8000 Opening the gas detector 1. Loosen the set screw (6). 2. Unscrew the lid (1) and take it off the gas detector. 3. Turn the handle (2) upward and pull out the PCB unit (3) containing the main electronics.
Installation in the H1 segment - Polytron 8000 Signal lines for explosion protection type Ex d The terminal of the PCB unit within the Ex d housing is assigned as follows. FB+ / Data A DATA A FB- / Data B DATA B N.
Installation in the H1 segment - Polytron 8000 4.4.1 Rewiring of the PCB unit in the Ex d housing The following information is only required if the Ex d housing has to be rewired (e.g. when replacing the PCB unit in the Ex d housing). Remote sensor Data-A Data-B...
Installation in the H1 segment - Polytron 8000 Applying the termination Use an RC element for termination. Properties of the RC element: Parameter Nom. Value Tolerance Unit Termination resistor +/- 2 % Ω Termination capacitor +/- 20 % µF 1. Apply the termination depending on the location of the gas detector within the H1 segment.
Commissioning - Polytron 8000 ≥ 8 LB IN ≥ 0.7 Nm ≥ 44 LB IN ≥ 5 Nm Fig. 1 Closing the Ex d enclosure with correct torques Commissioning - Polytron 8000 Checking the installation 1. Check for correct connection of the cables (see 4.3 Signal lines for explosion protection type Ex d) 2.
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Commissioning - Polytron 8000 a. Right-click on HOST PC (2) and choose Gerät hinzufügen. b. Highlight the driver for the connected Profibus interface. c. Choose OK. 5.2.3 Establishing the connection to the gas detector To establish the connection to the gas detector, the gas detector must be added to the Communication DTM.
Troubleshooting If all settings are correct, the connection status (1) changes to verbunden/connected Troubleshooting Fault analysis If communication with the gas detector cannot be established, check the following items: – Verify that the address (node) of the field device is the same as the address specified in the DTM.
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