Every exchange with the DynaFlex II Go— the commands you send and the responses and notifications it returns — uses the standard Multi-Interface Card Reader Platform (MMS) message format. This section defines how requests, responses, notifications, and file messages are framed and parsed. The format is the same across DynaFamily readers and is documented once in the shared reference.
Applies to: DynaFlex II Go
Settings & Information - Group 0xD1nn
Reference Section
Information Available
The host and the device communicate with each other by exchanging blocks of data called Messages, which are standardized wrappers containing a payload that is either a command Request, a command Response, an unsolicited Notification, or a File.
Programmer's Manual
The DynaFlex II Go uses the shared Dyna-family Multi-Interface Card Reader Platform (MMS) command set. This manual is a device-scoped map into the API & Command Reference with the sections this device relies on linked below.
How MMS requests, responses, and notifications are framed and parsed.
Data Types & Shared TLV Objects
The shared TLV and EMV objects the commands carry.
Commands
The MMS command set, scoped to the Go, with a supported-commands view.
Notifications
Asynchronous messages the Go sends during transactions, device events, and firmware updates.
Configurations
Configurable properties and parameters.
Status Codes & Responses
Result and error codes the device returns.
Security & Keys --> How the Go protects data and manages keys: DUKPT (3DES→AES), MAC, KSNs, encryption/decryption, and the PCI requirements like the 24-hour reset and device lock.
Compliance--> The Go's PCI PTS POI security policy, certifications, and the regulatory documentation for deployment.
NFC/MIFARE -->Working with contactless cards and tags — NFC/MIFARE pass-through and the supported card technologies (NTag, Classic, DESFire, Plus).
These sections detail a variety of information on OIDs, codes, tips & taxes and more.
Applies to: DynaFlex II Go
System Status Information - Property Group 2.3.1.nnn
Reference Section
Information Available
For modular management of device functions, information, and settings, this standard makes extensive use of Object Identifiers (also known as Object IDs or OIDs) as defined in ITU-T X.660 | ISO/IEC 9834-1.
Data Types & Shared TLV Objects
Data Types and Shared TLV Data Objects
This section defines the primitive and composed data types, TLV (Tag-Length-Value) data objects, file structures, and cryptographic key formats used throughout the device command set, including track data, display strings, EMV configuration file types (ARQC, ARPC, Batch, CA Public Keys), security parameters, TR‑31 key blocks, certificate and CSR file structures, and card emulation.
Applies to: DynaFlex II PED
Information in this group
Section
Information available
A list of primitive data types used by TLV data objects.
Information on loading this file type to control the behavior of the device’s EMV contact and contactless kernels when the device should support Offline Data Authentication (ODA).
Information on loading this file type to control the behavior of the device’s American Express contactless kernel when the card sends tag 9F70 and one or more DRL is defined. (Not supported on Expresspay 4.x)
This non-TLV data structure consists of four or five bytes that describes a security operation, including the algorithms and methods to be used in that operation.
MMS notifications are the asynchronous messages the DynaFlex II Go reader sends while a transaction is running, reporting progress, state changes, and completion. Find the Notification Group you are looking for below and follow the links in the table to jump to a specific notification.
This notification reports the final result of a transaction the host initiated using Command 0x1001 - Start Transaction.
Reference Section
Information Available
This notification reports the successful completion of firmware update operations the host initiated
This notification reports the failure of a Firmware Update command the host initiated.
This notification reports Firmware is up to date for host initiated update.
Reference Section
Information Available
This notification reports information about general state changes that occur within the device, outside the context of specific operations like transactions
The device sends this notification when the battery charge reaches 15 percent.
The device sends this notification one minute before it automatically powers down the device.
Reference Section
Information Available
This notification requests that the host take action during operations involving the device’s User Interface modules.
This notification shows that a UI operations involving the device’s User Interface modules is complete.
Reference Section
Information Available
This notification reports information about progress and state changes that occur during a Pass-Through Mode.
The DynaFlex II Go accepts the Multi-Interface Card Reader Platform (MMS)
command set — the messages you send to run transactions, read cards, manage keys
and files, and query or configure the reader. Full syntax, parameters,
responses, and examples are documented once in the shared reference; the
families below are the commands the Go supports, each linking into that
reference.
Applies to: DynaFlex II Go
Transaction - Group 0x10nn
Reference Section
Information Available
The host uses this command to start a payment transaction.
The Host uses this command to send commands and receive responses to and from a MIFARE Plus tag.
The host uses this command to direct the device to arm or disarm the barcode reader for reading a barcode outside the scope of a transaction.
The host uses this command to start a buzzer for playing a sequence of tones. Each sequence can have a minimum of 1 to maximum of 10 tones.
The host uses this command to prompt a cardholder for customer information.
The host uses this command to trigger the device to immediately show a pre-loaded image on the display.
The host uses this command to direct the device to immediately show a QR code on the display.
The host uses this command to trigger the device to immediately show a bitmap file the host includes as a parameter.
This command allows the host to bring up standalone pages.
The host uses this command to control the 4 LEDs of the device when the device is not in non-User Control LED states.
Card emulation is initiated by receiving a 0x1840 command from the host.
The host uses this command to send application-level APDUs to a PICC that supports ISO 14443-4 Protocol
The host uses this command to start sending unsecured files to the device for storage or processing
The host uses this command to request a file stored on the device.
The host uses this command to request the file information of a file stored on the device.
The host uses this command to request the deletion of a file stored on the device.
The host can use this command to change the device’s lock passcode.
The host uses this command to retrieve information about a key slot, including details about the key stored in that slot.
The host uses this command to provide a cardholder selection to the device when the device itself does not have a display or inputs to prompt the cardholder for a selection.
After entering the Pass-Through Mode, the host use this command to request the device to start polling for a Type A and Type B PICC until it detects a PICC or times out.
Large blobs of data uploaded to / downloaded from the device are referred to as “files” and share a common set of commands documented here, and special message type Data File Message.
The host uses this command to commit a file previously uploaded using Command 0xD801 - Load (Firmware File) into the device’s permanent memory after the device has authenticated the file.
The host uses this command to complete the ECDHE-ECDSA Key Exchange protocol, which enables the host and the device to generate the same TEMP KBPK key to use with Command 0xEF01 - Load Key Using TR-31 to load the Master Transport Key (MTK).
NFC/MIFARE Pass-Through - Group 0x11nn
User Interface - Group 0x18nn
Generic Pass-Through - Group 0x30nn
Device Control - Group 0x1Fnn
Banking Functions - Group 0x20nn
Settings & Information - Group 0xD1nn
File Operation - Group 0xD8nn
Process Files - Group 0xD9nn
Diagnostics & Utilities - Group 0xDFnn
Security - Grouo 0xEnnn
Manufacturing - Group 0xFnnn
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This section focuses on properties, which the host can either read from the device to retrieve device information (such as its PCI hardware ID, serial number, firmware revision numbers, etc.), or write to the device to change device behavior, or to store values for future reference.
The device uses this property to determine what character it should use when sending masked ISO/ABA track data.
The device sends this notification when the battery charge reaches 15 percent.
Reference Section
Information Available
Configure how the device runs financial transactions — EMV terminal and kernel parameters, supported entry methods, and amount, currency, and timeout handling.`
Continues the transaction group with the remaining financial/EMV properties, such as contactless and additional processing options.
Read the device's core identity and status: model name, serial number, firmware and boot versions, real-time clock, and operational state. These are mostly read-only values for identifying and health-checking the reader.
Reference Section
Information Available
The device's top-level firmware identifier — the composite firmware ID that ties together the individual component versions and checksums listed below.
Part number, version, and build details for the device's core application firmware — the main firmware that runs the reader.
Part number and version for the EMV firmware component that handles Level 2 EMV processing for contact and contactless transactions.
Reference Section
Information Available
Read-only hardware information reported by the device, such as model, part number, and hardware revision.
Reference Section
Information Available
This OID contains a 32-bit bitmap. Each bit indicates the status of a transaction key,
The device uses this property to report its security status.
Firmware Identification Information - Property Group 2.1.2.nnn
Hardware Information - Property Group 2.2.1.nnn Device
System Status Information - Property Group 2.3.1.nnn
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Configure Wi-Fi connectivity on WLAN-equipped models, including network SSID, security mode, and credentials. Applies only to devices with a WLAN radio.
Continues WLAN configuration with the remaining network properties, such as IP addressing and connection behavior.
Configure the USB interface on USB-connected devices, including communication mode and power behavior during USB suspend. Applies only when connected over USB.
Configure the device's cardholder-facing interface — display behavior, LEDs, buzzer, and prompts — including the UI configuration file.
Continues UI configuration with the remaining interface properties, such as the card-logos page and related on-screen elements.
Set or read the name the device advertises over Bluetooth LE, used to identify the reader when pairing and connecting.
Configure the device's security posture, including SRED/encryption behavior and key status.
Configure the device's system settings
A checksum identifying the contactless Level 1 kernel firmware, used to confirm which L1 kernel build is installed.
A checksum identifying the Discover D-PAS contactless kernel firmware installed on the device.
The identifier and version of the China UnionPay contactless kernel firmware.
Firmware and version information for the device's Wi-Fi (WLAN) module, on models equipped with a WLAN radio.
Identifies the custom user-interface package loaded on the device — which custom UI build (if any) is installed, and its version.
Firmware and version information for the device's NFC contactless module and controller.