# FAQs (/global/en/docs/Terminal/EMVL3/FAQs) **"Q1: If there is a cashback amount, how should 9F02 and 9F03 be transmitted?"** EMVL3 provides parameter `1F8166` for control. This parameter is used to identify whether the authorized amount (`9F02`) includes the cashback amount (`9F03`). If `9F02` includes `9F03`, then `9F03` must still be transmitted in the parameters. | Parameter Name | Length | Description | | | :----------------- | :----- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | Amount status flag | 1 | This parameter is used to identify the authorised amount (`9F02`) whether included cashback amount (`9F03`). \**Tag:*\* `1F8166` \**Format:*\* b1 \**Supported values:\*\* `00h`: Default values. The application should set amounts as following: `9F02` = purchase amount `9F03` = cashback amount Then emvl3 will update `9F02` itself (`9F02` = `9F02` + `9F03`). `01h`: The application should set amounts as following: `9F02` = purchase amount + cashback amount `9F03` = cashback amount \**Note:** Whether the authorised amount (`9F02`) includes cashback amount (`9F03`), the cashback amount (`9F03`) should be set. | | **"Q2: How to set up fallback?"** **Configuration for fallback from Contact (Chip) to Magnetic Stripe:** - First byte: Whether to disable fallback from Contact to Magnetic Stripe. - Second byte: Under which circumstances to run fallback. | Parameter Name | Length | Description | | | :------------------------------- | :----- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | CT to MSR Fallback Configuration | 3 | This data item allows configuration of Contact (Chip) to MSR fallback based on EMV, various card association, acquirer or regional (L3) rules. \**Tag:*\* `1F8122` \**Format:*\* b3 \**Default value:*\* 00 1F 00 \**Applies to:*\* CT EMV The format of this data item is as follows: \**Byte 1:*\* Disabled "Contact (Chip) Card to MSR Fallback" By default, "Contact to MSR fallback" is supported. However, this data item can be used to disable support for this featrue. **Possible Values** `00h`: Contact Card to MSR Fallback supported. This is the default if this data item is not present. `01`h: Disabled "Contact Card to MSR Fallback" support. If CT to MSR fallback is supported, then the standard method for fallback specified by EMV will always be supported. However, support for non-standard fallback methods can be configured via Byte 2. \**Byte 2:*\* Non-EMV Fallback Methods Supported. This byte can be used to configure only the nonstandard fallback methods that are usually outside the scope of EMV and are usually specified by the card associations, acquirers or regional rules. The format of this byte is as follows. Bit 8: RFU (must always be set to 0) Enable Fallback on Empty Aid Candidate list/Unknown AID Bit 7: Enable Fallback on Card Blocked Bit 6: Enable Fallback on App Blocked Bit 5: Enable Fallback on Chip Read Error during App Selection Bit 4: Enable Fallback on Chip Read Error during GPO Bit 3: Enable Fallback on Chip Read Error during Read Records Bit 2: Enable Fallback on Chip Read Error during Gen AC 1 Bit 1: Enable Fallback on Chip Read Error during Gen AC 2 \**Byte 3:*\* RFU | | **Configuration for Fallback from Contactless to Magnetic Stripe/Contact** | Parameter Name | Length | Description | | | :------------------------------------ | :----- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | CL to CT/MSR 'Fallback' Configuration | 1 | This data item allows configuration of Contactless to Contact and MSR fallback. \**Tag:*\* `1F8123` \**Format:*\* b1 \**Default value:*\* 80 \**Applies to:*\* Contactless The format of this data item is as follows: Bit 8: Enable when transaction amount exceed contactless limit amount Bit 7 \~ Bit 1: RFU | | Currently, only one scenario: Fallback occurs when the transaction amount exceeds the contactless limit amount. **"Q3: Regarding configuring \\"Always Callback for Application Selection\\", the documentation mentions two parameters: \`1F8164\` and \`1F8165\`. Do both parameters need to be set simultaneously?"** For configuring "Always Callback for Application Selection", use parameters `1F8164` and `1F8165`. | Parameter Name | Length | Description | | | :-------------------------- | :----- | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | App Selection Configuration | 1 | This parameter indicates whether the kernel callback Application Selection Function. \**Tag:*\* `1F8164` \**Format:*\* b1 \*\*The default situation:** For contactless, will not callback, CL kernel auto-select For contact(EMV), will callback when needed: (a) If a selection is to be made from multiple AIDs or (b) There is a single AID for which cardholder confirmation is required \*\*This parameter allow extern usage:** Bit 8: Always callback App Selection Function for CT. Bit 7: Always callback App Selection Function for CL. Bit 6 \~ Bit 1: RFU | | | Parameter Name | Length | Description | | | :--------------------------- | :----- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | Callback Function Indicators | 4 | This parameter indicates whether the kernel callback, and you can set card confirm callback in this parameter. \**Tag:*\* `1F8165` \**Format:*\* b4 \**Applies to:*\* Contact and Contactless \*\*The default situation:** 40 00 38 00 For Callback App Selection Function, will have same function like `1F8164`. For Card Confirm Function, this callback is performed in different positions in Contact and Contactless. The detailed information is as follows: 1) For Contact, the Card Confirm Function will perform after read application data. 2) For Contactless, the Card confirm Function will perform after kernel process, which Application Cryptogram(TC/ARQC) had been generated, and you can remove the card. So if you need to change some transaction data (like DCC may need to change amount and national currency code) in this callback, you should return L3\_ERR\_FAIL and run NAPI\_L3PerformTransaction with new transaction data again. \*\*This parameter allowed extern usage:** **Byte 1: Contact Callback Indicators** bit 8: Always callback App Selection Function for CT bit 7: Support callback Card Confirm Function for CT bit 6 – bit 1: RFU **Byte 2: RFU** **Byte 3: Contactless Callback Indicators** bit 8: Always callback App Selection Function for CL bit 7: Support callback Card Confirm Function for CL bit 6: Support callback get APDU Function for CL bit 5: Support callback after final select Function for CL bit 4: Support friendly transaction UI Callback for CL bit 3: Support card transfer prompt UI callback for CL bit 2 - bit 1: RFU **Byte 4: RFU** | | Only one of these parameters needs to be set for functionality to take effect; setting both is not necessary. **"Q4: How to configure EMVL3 for external card polling versus internal card polling?"** Set the detected card type into `1F8121`. This signifies the EMVL3 external card polling mode, and EMVL3 internally will not perform card polling operations anymore. When using external polling, the `detectCard` interface needs to be called. **"Q5: How to set the QPS limit? Why is it that even when the transaction amount is less than the set QPS limit, it still requires PIN/signatrue (i.e., not contactless without PIN/signatrue)?"** The QPS limit is set using `1F8124`, and it only applies to Credit/Quasi-Credit cards. It is not effective for DEBIT Cards. **"Q6: How to allow a chip card to be swiped via MSR (Magnetic Stripe Reader) without triggering fallback conditions?"** Set `1F8125` to `01`. | Parameter Name | Length | Description | | | :---------------------------------------------------- | :----- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | - | | Allow MSR transaction on Chip Card (without Fallback) | 1 | As per EMV, if a dual card (Chip + MSR) is swiped the Reader is supposed to perform a Contact EMV transaction and not a MSR transaction. The only condition under which an MSR swipe transaction is allowed is a fallback condition. By default, this is the behavior of the reader. This data item can be used to override this EMV restriction and allow an MSR transaction even though a dual card (Chip + MSR) is swiped. \**Tag:*\* `1F8125` \**Format:*\* b1 \**Applies to:*\* MSR **Possible Values** `00h`: Do not allow MSR transactions on chip cards without a fallback condition. This option complies with the CT EMV specification. This will be the default behavior if this data item is missing. `01h`: Allow MSR transaction on chip card without a fallback condition (which is non-compliant to EMV). | | **"Q7: How to set the number of retry attempts before fallback during a contact transaction?"** For contact transactions, it allows retrying to read the card again before FALLBACK. This can be configured using `1F8127`. If not set, the default number of retries is 3 times. This only applies to contact transactions. **"Q8: How to control the LED lights and audio during the transaction process? What are the specific lighting patterns for LED Mode 1 and Mode 2?"** Set `1F8129`. Used for contactless. | Parameter Name | Length | Description | | | :----------------------- | :----- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - | | LED and Audio indicators | 3 | This parameter is added to meet a customer's requirement that if you don't want any LED display during the transaction. \**Presence:*\* Optional (if this parameter is not included, LED can turn on normally). LED Indicator control (optional) (This TAG is mainly used for Contactless, other types are invalid) \**Tag:\*\*`1F8129` \**Format:** b3. \**Default value:*\* C0 XX 00 **Byte 1: Enable/Disable LED/AUDIO indicators** bit 8: 1: Enable LED indicators; 0: Disable LED indicators bit 7: 1: Enable Audio indicators; 0: Enable Audio indicators bits 6-1: RFU \*\*Byte 2: LED indication mode:\*\* bit 8: 1: Use EMVCo Option 1 (Visa Europe compliant); 0: Use EMVCo Option 2 bit 7 \~ bit 1: RFU **Byte 3: RFU** | | Mode 1: 1 LED on during reading, 1-4 LEDs on upon successful read. Mode 2: 1-2 LEDs on during reading, 1-3 LEDs on upon successful read. **"Q9: How to set up a simplified flow?"** Set `1F8128`. Applies to both contactless and contact.