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  <xs:element id="omcl_ResearchAndDevelopmentTable" abstract="true" name="ResearchAndDevelopmentTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="omcl_ResearchAndDevelopmentLineItems" abstract="true" name="ResearchAndDevelopmentLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_CapitalizedCostSoftwareToBeSoldLeasedOrMarketedEstimatedAmortizationExpenseAfterYearFour" abstract="false" name="CapitalizedCostSoftwareToBeSoldLeasedOrMarketedEstimatedAmortizationExpenseAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_WellsFargoSecuritiesLLCCitizensBankNAAndJPMorganChaseBankNAMember" abstract="true" name="WellsFargoSecuritiesLLCCitizensBankNAAndJPMorganChaseBankNAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_WellsFargoSecuritiesLLCJPMorganChaseBankNAPNCCapitalMarketsLLCAndTDSecuritiesUSALLCMember" abstract="true" name="WellsFargoSecuritiesLLCJPMorganChaseBankNAPNCCapitalMarketsLLCAndTDSecuritiesUSALLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_SecuredOvernightFinancingRateSOFRApplicableMarginMember" abstract="true" name="SecuredOvernightFinancingRateSOFRApplicableMarginMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_OneMonthSecuredOvernightFinancingRateSOFRMember" abstract="true" name="OneMonthSecuredOvernightFinancingRateSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_OneMonthSecuredOvernightFinancingRateSOFRApplicableMarginMember" abstract="true" name="OneMonthSecuredOvernightFinancingRateSOFRApplicableMarginMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" abstract="false" name="LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantAdjustedEBITDAThreshold" abstract="false" name="DebtInstrumentCovenantAdjustedEBITDAThreshold" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantMaximumSecuredNetLeverageRatio" abstract="false" name="DebtInstrumentCovenantMaximumSecuredNetLeverageRatio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantMinimumInterestCoverageRatio" abstract="false" name="DebtInstrumentCovenantMinimumInterestCoverageRatio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="omcl_ConvertibleSeniorNotesDue2025Member" abstract="true" name="ConvertibleSeniorNotesDue2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ConvertibleSeniorNotesDue2029Member" abstract="true" name="ConvertibleSeniorNotesDue2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ConvertibleNoteHedgeRightsMember" abstract="true" name="ConvertibleNoteHedgeRightsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_DebtInstrumentAccordionFeatureIncreaseLimit" abstract="false" name="DebtInstrumentAccordionFeatureIncreaseLimit" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentRedemptionFaceAmountOfNotesThatMustBeOutstanding" abstract="false" name="DebtInstrumentRedemptionFaceAmountOfNotesThatMustBeOutstanding" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentConvertibleNumberOfSharesIssuable" abstract="false" name="DebtInstrumentConvertibleNumberOfSharesIssuable" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="omcl_AdjustmentsToAdditionalPaidInCapitalConvertibleNoteHedge" abstract="false" name="AdjustmentsToAdditionalPaidInCapitalConvertibleNoteHedge" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DeferredTaxAssetConvertibleDebtHedge" abstract="false" name="DeferredTaxAssetConvertibleDebtHedge" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_SalesTypeAndDirectFinancingLeasesLeaseReceivableToBeReceivedAfterYearFour" abstract="false" name="SalesTypeAndDirectFinancingLeasesLeaseReceivableToBeReceivedAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_A2009PlanMember" abstract="true" name="A2009PlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_A2025RepurchaseProgramAnd2016RepurchaseProgramMember" abstract="true" name="A2025RepurchaseProgramAnd2016RepurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_A2025RepurchaseProgramMember" abstract="true" name="A2025RepurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_A2016RepurchaseProgramMember" abstract="true" name="A2016RepurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsPurchasedInPeriodWeightedAveragePrice" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsPurchasedInPeriodWeightedAveragePrice" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingTermAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingAggregateIntrinsicValueAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingAggregateIntrinsicValueAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageRemainingTermAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageRemainingTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_RestrictedStockRSAsRestrictedStockUnitsRSUsAndPreformanceSharesPSUsMember" abstract="true" name="RestrictedStockRSAsRestrictedStockUnitsRSUsAndPreformanceSharesPSUsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_FutureGrantsAndAwardsMember" abstract="true" name="FutureGrantsAndAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
