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  <xs:element id="omcl_SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate" abstract="false" name="SharebasedCompensationArrangementbySharebasedPaymentAwardFairValueAssumptionsEstimatedForfeitureRate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="omcl_USGovernmentHospitalsMember" abstract="true" name="USGovernmentHospitalsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_A1997EmployeeStockPurchasePlanMember" abstract="true" name="A1997EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ScheduleofSharebasedCompensationFutureIssuanceofSharesTableTextBlock" abstract="false" name="ScheduleofSharebasedCompensationFutureIssuanceofSharesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <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_BusinessCombinationAcquiredIntangibleAssetsMeasurementInput" abstract="false" name="BusinessCombinationAcquiredIntangibleAssetsMeasurementInput" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageRemainingTermAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageRemainingTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_RevenueFromContractWithCustomerTimingAndClassificationOfRevenueCategoriesTableTextBlock" abstract="false" name="RevenueFromContractWithCustomerTimingAndClassificationOfRevenueCategoriesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsPurchased" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsPurchased" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="omcl_ScheduleOfDebtIssuanceCostsNetTableTextBlock" abstract="false" name="ScheduleOfDebtIssuanceCostsNetTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <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_TechnicalServicesMember" abstract="true" name="TechnicalServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_LesseeOperatingLeaseLeaseAssumptionsTableTextBlock" abstract="false" name="LesseeOperatingLeaseLeaseAssumptionsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="omcl_AmortizationOfDebtIssuanceCostsExcludingConvertibleDebt" abstract="false" name="AmortizationOfDebtIssuanceCostsExcludingConvertibleDebt" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_LesseeOperatingLeaseSupplementalCashFlowInformationTableTextBlock" abstract="false" name="LesseeOperatingLeaseSupplementalCashFlowInformationTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="omcl_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingAggregateIntrinsicValueAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingAggregateIntrinsicValueAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_ContractWithCustomerLiabilityCustomerAdvancesAndDepositsCurrent" abstract="false" name="ContractWithCustomerLiabilityCustomerAdvancesAndDepositsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionMaximumPeriod" abstract="false" name="RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionMaximumPeriod" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="omcl_OneTimeStockRepurchaseSeptember2020Member" abstract="true" name="OneTimeStockRepurchaseSeptember2020Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DistributionAgreementMember" abstract="true" name="DistributionAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilityNoncurrent" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilityNoncurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_FuturegrantsandawardsMember" abstract="true" name="FuturegrantsandawardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_GroupPurchasingOrganizationFees" abstract="false" name="GroupPurchasingOrganizationFees" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_FiniteLivedIntangibleAssetsCurrencyTranslationAdjustments.IncreaseDecrease" abstract="false" name="FiniteLivedIntangibleAssetsCurrencyTranslationAdjustments.IncreaseDecrease" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentAssetsOther" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentAssetsOther" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilities" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_AccruedGroupPurchasingOrganizationFees" abstract="false" name="AccruedGroupPurchasingOrganizationFees" 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_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedCompensation" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedCompensation" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <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_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedLiabilities" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_ShareBasedPaymentArrangementAwardExcludingOptionCostNotYetRecognizedAmount" abstract="false" name="ShareBasedPaymentArrangementAwardExcludingOptionCostNotYetRecognizedAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_ProceedsFromPaymentsForCustomerFundsNet" abstract="false" name="ProceedsFromPaymentsForCustomerFundsNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_ConsumablesMember" abstract="true" name="ConsumablesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_IncreaseDecreaseInOperatingLeaseLiabilities" abstract="false" name="IncreaseDecreaseInOperatingLeaseLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantPeriod2Member" abstract="true" name="DebtInstrumentCovenantPeriod2Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ChangeInDebtIssuanceCostsNetRollForward" abstract="true" name="ChangeInDebtIssuanceCostsNetRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="omcl_A340BLinkBusinessMember" abstract="true" name="A340BLinkBusinessMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_The2016RepurchaseProgramMember" abstract="true" name="The2016RepurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_DebtInstrumentConvertibleNumberOfSharesIssuable" abstract="false" name="DebtInstrumentConvertibleNumberOfSharesIssuable" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="omcl_AmortizationOfOperatingLeaseROUAsset" abstract="false" name="AmortizationOfOperatingLeaseROUAsset" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_BusinessCombinationBasePurchasePrice" abstract="false" name="BusinessCombinationBasePurchasePrice" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantTermsDomain" abstract="true" name="DebtInstrumentCovenantTermsDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_ConvertibleSeniorNotesMember" abstract="true" name="ConvertibleSeniorNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_A2016and2014ShareRepurchaseProgramsMember" abstract="true" name="A2016and2014ShareRepurchaseProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_IncrementalLoanFacilityMember" abstract="true" name="IncrementalLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_PaymentsforSoftwareForExternalUse" abstract="false" name="PaymentsforSoftwareForExternalUse" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" 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_ContractwithCustomerLiabilityCurrentGross" abstract="false" name="ContractwithCustomerLiabilityCurrentGross" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_DebtInstrumentCovenantPeriod1Member" abstract="true" name="DebtInstrumentCovenantPeriod1Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="omcl_AccruedLiabilitiesRebatesandLeaseBuyoutsCurrent" abstract="false" name="AccruedLiabilitiesRebatesandLeaseBuyoutsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="omcl_SalesTypeLeaseReceivableComponentsTableTextBlock" abstract="false" name="SalesTypeLeaseReceivableComponentsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="omcl_ScheduleOfInterestExpenseDebtTableTextBlock" abstract="false" name="ScheduleOfInterestExpenseDebtTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="omcl_ConnectedDevicesSoftwareLicensesAndOtherMember" abstract="true" name="ConnectedDevicesSoftwareLicensesAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingTermAbstract" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingTermAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
</xs:schema>
