Product catalog - TURCK

FOUNDATION fieldbusCable technology – BasicsA two or three wire cable is prescribed byIEC 61158-2 as the transmission mediumfor transmission energy and data.Cable parametersElectrical data and permissible cable typesare not prescribed. Cable parametersdetermine the achievable fi eldbus propertiessuch as the distances to be covered,number of connectable stations andelectromagnetic compatibility.In the following table (Tab. 1) we comparethe four standard cable types (at 25 °C):Type A Type B Type C Type D(Reference)Cable design Twisted One or Multiple twisted Multiple nonconductorpair multiple twisted pairs, not shielded twisted pairsconductor pairs,not shieldedoverall shieldConductor cross-section (nominal) 0.8 mm 2 0.32 mm 2 0.13 mm 2 1.25 mm 2(AWG 18) (AWG 22) (AWG 26) (AWG 16)Loop impedance (DC current) 44 Ω/km 112 Ω/km 264 Ω/km 40 Ω/kmWave resistance at 31.25 kHz 100 Ω ± 20 % 100 Ω ± 30 % not specifi ed not specifi edWave attenuation at 39 kHz 3 dB/km 5 dB/km 8 dB/km 8 dB/kmCapacitive asymmetry 2 nF/km 2 nF/km not specifi ed not specifi edGroup delay distortion (7,9...39 kHz) 1.7 µs/km not specifi ed not specifi ed not specifi edDegree of shield coverage 90 % not specifi ed not specifi ed not specifi edRecommended network expansion 1900 m 1200 m 400 m 200 m(incl. spur lines)Tab. 1 Cable types to IEC 61158-2Use of the individual cable typesCables conforming to the minimumrequirements of type A, should be usedfor new installations. Cable types Cand D should only be used in so-called“Retrofi t Applications” (usage of cablealready installed) involving only very limitednetwork extensions. It is necessary toconsider that in these cases the immunityto interference during data transmissionmay not meet the demands described inthe standard.the types and limit values listed in Tab. 1,but its particularly suitable for FOUN-DATION fi eldbus and PROFIBUS-PAfi eldbus systems. All of TURCK’s cablesfor fi eldbuses compliant with IEC 61158-2feature optimum quality even exceedingtype A requirements.Maximum cable lengths, spur linesEach fi eldbus installation must follow adefi ned set of rules, the “Network confi -guration rules” (see IEC 61158-2, Chap.11.2.2). The following limit values forpermissible attenuation, refl ection anddistortion (rule 8), as well as the maximumsignal delay (rule 4) are listed (see Tab. 2).Installations conform to the FISCOmodelInstallations conform to the FISCO modelare not subject to any technical safety limitations,if the limit values defi ned in Tab. 1are observed. Operation outside of theselimit values is not generally excluded, butrequires that each case is consideredindividually.For example, the TURCK long distance“Cable FBY../LD” is not comparable withAttenuation between any two bus interfaces (at 31.25 kHz)10.5 dBAttenuation distortion a (f = 39 kHz) – a (f = 7.8 kHz),6 dBmonotonic increasing with frequencyRefl ection factor at any point (7.8...39 kHz) 0.2Signal delay between any two bus interfaces 640 µsTab. 2 Limit values for attenuation, distortion, refl ection and propagation delay122 /0309 Hans Turck GmbH & Co.KG • Witzlebenstraße 7 • 45472 Mülheim/Ruhr • Germany • Tel. +49 (0)208 4952-0 • Fax +49 (0)208 4952-264 • more@turck.com • www.turck.com