ABB ACS310 - Fieldbus Modules for ABB Drives; Common Recommendations

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Quickstart Guide
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ABB PLC and drives integration using Modbus RTU
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ModbusRTU‐8‐ PLCanddrivesintegration
FieldbusmodulesforABBdrives
The following ABB drives Modbus RTU modules have an option to activate built‐in end termination and pull‐
up/pull‐downresistors.
 RMBA‐01(usedwithforinstanceACS550andACS800)
 FSCA‐01(usedwithforinstanceACS880andACSM1)
ThefollowingABBdrivesModbusRTUmoduledoesnothaveanoptiontoactivatebuil
t‐inendresistorsincluding
pull‐up/pull‐downresistors.
 FMBA‐01(usedwithforinstanceACS355)
Since the built‐in end termination of the modules (RMBA‐01 and FSCA‐01) automatically also activates pull‐
up/pull‐downresistors,itisrecommendedtoskipthebuilt‐inoption.
Itis  recomm
ended to connect a separateendtermination resistor to the first node (i.e. the PLC COMinterface)
andthelastnode(i.e.thelastdriveonthebus).
Forconnectionexamples,seechapter“Installationexamples”.
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Commonrecommendations
Note!Thefollowingbulletsareonlyrecommendationsandnogeneralrules.
 Installationwheretotalcablelengthismorethan50 m
o UseCPUAC500ratherthanAC500‐eCoorAC500‐eCowithTK506RS485isolatorforCOM1.
 Installationwherethereisariskthatgroundconnectionsindiffer
entnodescouldvaryinvoltagepotential
(typicallyinshipinstallationsorwithcablelengthsmorethan50m).
o UseCPUAC500anddonotconnectgroundcable,onlyshield →2‐wiresolution,oruseAC500‐eCo
withTK506RS485isolatorforCOM1.
 WhenAC500‐eCoisused
o Use of 3‐wire conne
ction is recommended because the COM interface is not opto‐isolated,
oruseAC500‐eCowithTK506RS485isolatorforCOM1.
o Use of cable length more than 50m should be realized with repeaters,
oruseAC500‐eCowithTK506RS485isolatorforCOM1.
 Cabletyp
e
o Use only cables with twisted pair wires and braided shields. Foil shields are not robust enough,
cannotbecontactedwellandhavepoorHF(HighFrequency)properties.
o Groundthecableshield directlywithaclipwhenenteringtheswitch‐gearcabinet.Donotcutthe
shieldun
tilthecablereachestheconnectedmodule. 
o TheconnectionbetweenthePEbarandtheshieldbarmusthavelowimpedance.
o UseABBcableTK505whensuitableforeasyinstallation.