261 SERIAL INTERFACE Universal Serial Interface with standard 25way D series sockets EUROTHERM 261 SERIAL INTERFACE A B TX POWER TX abc
261 Serial Interface Digital communications: Convertor and/or Isolator Convert/isolate between RS232/RS485 (RS422) and RS232/RS485 (RS422) RS485 (RS422) 4 and 5 wire connection Bidirectional operation with LED s to indicate output activity Free standing with IEC supply connector, ideal for personal computers Expander: Tristate outputs enable multiple expansion from a single computer port Baud rates: 1109600 Dimensions: 155W x 65H x 168.5D mm Technical specification for safety purposes Equipment ratings Supply voltage: 115 or 230Vac 15%, +10%, (98 to 126Vac or 207 to 264Vac) Supply frequency: 48 to 62Hz Power consumption: 20 Watts maximum Low level I/O: Digital communications connections are intended for low level signals at less than 42V Fuse (in IC connector) Suitable fuses are 250mA, T type, (IEC 127 timelag type) Environmental ratings Operating temperature: 0 to 50 C. Ensure that the unit has adequate ventilation Relative humidity: 5 to 90% Rh, noncondensing Atmosphere: This product is not suitable for use above 2000m or in explosive or corrosive atmospheres Electrical safety Safety standard: Meets EN 61010, Installation category II, pollution degree 2 Voltage transients on the mains power connected to this product must not exceed 2.5kV Do not operate this unit in an environment of electrically conductive pollution, (e.g. carbon dust) Isolation: The two channels of digital communications have reinforced isolation between the mains supply and between each channel This provides protection against electric shock Safety symbols Various symbols are used on this product with the following meaning: Caution, (refer to the accompanying documents) This equipment is protected throughout with double or reinforced insulation Equipment protected by reinforced insulation does not require a protective earth connection.
SAFETY and EMC INFORMATION Please read this information before installing the 261 Serial Interface This product meets the requirements of the European Directives on Safety and EMC, however it is the responsibility of the installer to ensure the safety and EMC compliance of any particular installation. Safety This controller complies with the European Low Voltage Directive 73/23/EEC, amended by 93/68/EEC, by the application of the safety standard EN 61010(93). Electromagnetic compatibility This controller conforms with the essential protection requirements of the EMC Directive 89/336/EEC, amended by 93/68/EEC, by the application of a technical construction file. INSTALLATION REQUIREMENTS FOR EMC This unit satisfies the emissions and immunity requirements for residential, commercial and light industrial environments. To ensure compliance with the European EMC Directive certain installation precautions are necessary as follows: For general guidance refer to Eurotherm Controls EMC Installation Guide, HA025464. Routing of wires To minimise the pickup of electrical noise, digital communications cables should be routed away from highcurrent power cables. The use of shielded cables with the shield grounded at both ends is recommended. INSTALLATION AND SAFETY INSTRUCTIONS Caution! Hazardous voltages exist within this unit when connected to the supply. Always ensure that the supply is disconnected before opening the case. If case should become damaged in any way, immediately disconnect from the supply and return to Eurotherm Controls for repair. Personnel Installation must only be carried out by qualified personnel. Voltage rating The operating supply voltage of this unit has been factory selected as either 115 or 230V ac. This setting is indicated on the rear of the unit. If you want to change the setting, see Changing the Supply Voltage below. The maximum continuous voltage supply voltage with respect to ground must not exceed 264Vac. Voltage transients on this supply must not exceed 2.5kV. Where occasional transients over 2.5kV are expected or measured, the installation should be protected with a transient limiting device. These units will typically include gas discharge tubes and metal oxide varistors that limit and control voltage transients on the supply line due to lightning strikes or inductive load switching. Devices are available in a range of energy ratings and should be selected to suit conditions at the installation.
Changing the supply voltage By the following procedure the nominal supply voltage may be set to either 115 or 230Vac. After disconnecting from the supply, remove the two screws in the bottom of the case. This will allow the top half of the case to be removed. Between the two transformers is the supply voltage selection switch. This switch has two positions; 115 and 230. Select the required supply voltage. The rear panel has an area that indicates the selected supply voltage. Use TippEx or similar and an indelible marker pen to change the indication to reflect the new setting. Reassemble the case using the two case fixing screws. 422 and 485 Transmission Line Termination For correct operation of RS422 and RS485 networks the two extremes of the communication cable transmission lines should be terminated with 120 ohm resistors. This is to prevent the reflection of signals due to the impedance mismatch that would otherwise occur. These reflection signals will cause unreliable operation. Note that these termination resistors have no effect on RS232 operation. The 261 unit includes internally selectable termination resistors. As it is most likely that the 261 is at the extremes of a network, the termination resistors have been selected as a factory default setting. If it is required to place the termination resistors at another part of the network, please deselect the termination resistors using the following procedure. After disconnecting from the supply, remove the two screws in the bottom of the case. This will allow the top half of the case to be removed. At the front of the unit, close to the 25 way D connectors are the termination resistor selection links, LK 1 and LK 9. To remove the termination resistor from Channel A, remove LK 1. To remove the termination resistor from Channel B, remove LK 9. The black plastic link may be pulled off the two posts to disconnect the termination resistor. Store the link by reinserting it on just one of the posts leaving the other one exposed. Reassemble the case using the two case fixing screws. Voltage Select Switch LK4A, 6A 422 HELD LK4B, 6B 422 TRISTATES LK4A LK6A Tristate control link LK4 LK4B LK6B Tristate control link LK6 PLA LK1 LK9 PLB Link 1 Connector Port A Connector Port B Link 9
422 and 485 Tristate control The transmit circuitry used in the 422/485 mode is capable of disconnecting itself from the output lines when no signal is being transmitted. This facility is not required in the situation when the unit is being used to convert from an RS232 source and is inhibited by default when the unit is manufactured by fitting the links into the A position. If it is necessary to make use of this facility this can be done by moving link 4 or 6 from the A position to the B position. The only time that tristating of transmit lines is required is if there are several different units requiring access to these lines. TX Inhibit TX inhibit is a facility on RS 485 to enable a computer to place the output driver into the high impedance state. The inhibit is enabled by connecting the TX INHIBIT pin to the pin in the cable plug. In normal applications this pin is left open circuit. In this case the output automatically goes high impedance 10ms after the last transmission. (If low speed is enabled then the time out period is increased to 100ms.) Low Speed Connect the LOW SPEED pin to for transmission speeds below 1200 Baud. Connections are made in the cable plug. Schematic diagram SOCKET CONNECTIONS A B SOCKET CONNECTIONS RS 485 RS232 RS 232 RS485 TX 2 7 2 TX RX+ RX 3 7 RX 16 3 RX RX+ 16 RX TX+ 12 TX 13 12 TX+ TX INHIBIT 19 13 TX LOW SPEED (Connect to Common for Baud Rate <1200) 18 250V A.C ISOLATION 19 18 TX INHIBIT LOW SPEED Service and repair This controller has no user servicable parts. Contact your nearest Eurotherm Controls agent for repair. Order codes 261 230. For 220/240V operation 261 115. For 110/120V operation
EUROTHERM CONTROLS LIMITED UK SALES OFFICE Eurotherm Controls Ltd Faraday Close Durrington Worthing BN13 3PL United Kingdom Sales: Tel. +44 (0)1903 695888 Technical: Tel. +44 (0)1903 695777 Fax +44 (0)1903 695666 http://www.eurotherm.co.uk Sales and support in over 30 countries worldwide Enquiries/orders to: Eurotherm Controls Ltd Faraday Close Durrington Worthing BN13 3PL United Kingdom Tel. +44 (0)1903 268500 Fax +44 (0)1903 265982 Copyright Eurotherm Controls Limited 1990 All rights strictly reserved. No part of this document may be stored in a retrieval system, or any form or by any means without prior written permission from Eurotherm Controls Limited. Every effort has been taken to ensure the accuracy of this specification. However in order to maintain our technological lead we are continuously improving our products which could, without notice, result in amendments or omissions to this specification. We cannot accept responsibility for damage, injury loss or expenses resulting therefrom. Part No. HA021448 Issue 5 Printed in England 1299