> ## Documentation Index > Fetch the complete documentation index at: https://devzone.nayax.com/llms.txt > Use this file to discover all available pages before exploring further. # Marshall C# SDK Release Notes > Track Marshall C# SDK changes as they ship. Nayax logs Marshall C# SDK changes on this page as they ship. Subscribe to the RSS feed using the icon at the top of the page to get notified of new entries. Release notes are organized into two categories to help you evaluate the impact of each update: * **Improvements**: New APIs, expanded feature support, and performance enhancements. * **Fixes**: Resolved bugs and reliability improvements. ### Low-level serial cleanup Consolidated serial rx handling in `lowlevel_serial_t`: head-only framing, a poll-friendly sleep, and a named reader thread. ### Link and vend flow reliability Fixed a link-down issue in `vmc_link` where a missed ack left a packet pending forever and stopped keepalive; retransmit is no longer gated on transmit exceeding receive. * `vmc_vend_t` now handles `session_end` and `send_transfer_data` globally in any state, making the vend flow state more robust. ### Version history Every earlier C# SDK version, condensed to one line. See the current version above for full detail and links. | Version | Summary | | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | 0.0.5.19 | Improved link reliability and fixed false retransmissions | | 0.0.5.18 | Fixed a race condition between the rx and tx threads on `m_pending_tx_msg` access | | 0.0.5.17 | Added the `pre_auth_amount_config` (0x8c) vend sub-command, including the message class, decode/encode support, a factory method, event handling, and the public API; added demo menu options to align with the Java SDK (check balance, prepaid pay, pre-auth config, display message, close socket) | | 0.0.5.16 | Multi-vend max products per Marshall message are now calculated from the negotiated max message size; fixed the `session_end` timeout expiring too soon, which caused `reader_always_on` to fire early | | 0.0.5.15 | Aligned the C# SDK with the Java SDK across all modules: fixed transfer\_data bitmap constants and several encode bugs (`msg_time_rsp_t`, `msg_setup_max_min_prices_t`, `msg_remote_selection_t`, `msg_expansion_t`, `msg_reader_state_t`), added missing message classes and factory dispatch for vposm\_ext/ev\_ext messages, added `consumer_id` and other transfer\_data fields, and fixed numerous session, socket, and general-module bugs across `vmc_vend_t`, `vmc_general_t`, `vmc_socket_t`, and `vmc_link` | | 0.0.5.14 | Added real-time price change support for always-idle mode, even after the reader is already enabled, and a sanity check so `vend_request` and `close_session` return a boolean value and reject a price exceeding the permitted amount (65k when `long_price` is disabled); fixed a `session_id` decode issue on `msg_single_vend_t` and updated multi-vend request logging | | 0.0.5.13 | Aligned the C# SDK with the Java SDK; fixed `multi_vend_session_close` encoding | | 0.0.5.12 | Added protection against vend, socket, and general actions being issued when there is no link, preventing unnecessary crashes; optimized `eth_port` logging | | 0.0.5.11 | Removed an unnecessary and alarming "spurious ack" warning; fixed `eth_port` to recover when VPOS restarts but the socket does not close on the VMC side, by closing and reconnecting | | 0.0.5.10 | Fixed multi-vend multi-session packet encoding | | 0.0.5.09 | Fixed a potential packet loss from buffer wraparound that triggered retransmission and a bug where card data was not cleared after a transaction ended; `eth_port` is now functional | | 0.0.5.08 | Added enhanced display control (VPOSM) with legacy support for VPOS Touch devices and updated the sample application to support various display control layouts; stabilized the `eth_port` implementation | | 0.0.5.07 | Fixed frame-size detection with better sanity checks to support varying Marshall message sizes; added a `flush()` call to the port interface | | 0.0.5.06 | Added site ID and brand name transfer to the machine via transfer data and a new technician-mode command to open the door remotely; fixed long price for a single product | | 0.0.5.05 | Added brand selection and custom `transaction_id` generation | | 0.0.5.04 | Fixed an issue receiving `on_begin_session` on the latest SDK | | 0.0.5.03 | Added long price support (VPOSM) and QR third-party authorization support; fixed the negative price display issue | | 0.0.5.02 | Removed a CPU starvation warning that was confusing implementers | | 0.0.5.01 | Removed `lowlevel_serial`; you now inject a `serial_port_i` implementation (a working `pc_port.cs` is provided); fixed the VPOS serial number being returned as raw bytes instead of a correctly arranged string | | 0.0.4.23 | Fixed a re-transmission bug in buffer management that could lose consecutive packets arriving at the same time, an `mdb_rsp` parsing bug (Marshall master), a `lowlevel_serial` buffer management bug, and a string TLV decoding bug affecting transfer\_data parsing | | 0.0.4.22 | Added a `session_id` field to `vend_session_t` for multi-session reference; fixed an error parsing `msg_display_event_t` that skipped the user callback | | 0.0.4.21 | Fixed `card_balance` decoding and possible crashes parsing transfer\_data, including variable-length integer fields; changed the .NET version to 4.6.2 | | 0.0.4.20 | Added a logger API to dump raw data to a log file | | 0.0.4.19 | Fixed an undefined state machine state when `on_begin_session` arrived without a session starting, and deadlock risks from calling the API regardless of link state or stalling a callback while waiting for `end_session`; added the ability to send transfer data throughout the transaction starting at card detection, and added SDK configuration logging | | 0.0.4.17 | Added check-balance session type, card sub type and card balance transfer\_data, vend discount/final price calculation, and support for switching to an info session on always-idle setups; fixed e-receipt not working on multi-session setups, a race condition between rx and tx threads causing retransmission of an already-acked packet, and a possible crash when losing communication while sending `reader_enable` | | 0.0.4.16 | Fixed a multi-instance bug affecting both the sample application and the SDK | | 0.0.4.15 | Added the ability to instantiate multiple Marshall links | | 0.0.4.14 | Fixed the item price and code API type (integer to short) and a crash when cancelling a session after the card is presented but before vend is requested | | 0.0.4.13 | Fixed a transfer\_data parsing error that missed several tags | | 0.0.4.12 | `session_status` on the session object is now filled in by the SDK to report the transaction cancellation reason; fixed session cancel in always-idle mode; optimized `lowlevel_serial` CPU usage | | 0.0.4.11 | Added packet dumps on rx re-arrangement for debugging; improved `lowlevel_serial` handling under stress | | 0.0.4.10 | Added `vend_status(bool)` for explicit vend success, the total charged (and discount, if any) on the session structure, and absolute POSIX timestamps in log lines; renamed `Log.initialize()` to `Log.stream()`; fixed a vend-cancel timing bug and a false CPU warning on SDK initialization | | 0.0.4.9 | Added an extra data parameter to the `onStatus` API and `device_not_available_reason` enums; fixed a faulty transfer\_data parsing issue; the sample application now shows a human-readable status code and extra VPOS info on `onReady` | | 0.0.4.8 | Added `Log.console(boolean)`, new transfer\_data fields (main and POS firmware versions, Monyx ID, default credit), new device status enums, and the `onSessionTimeout(id)` event; reworked the sample application | | 0.0.4.7 | Added `unit_of_measure` enum values to `vmc_vend`; aligned log output between terminal and file | | 0.0.4.6 | Improved `lowlevel_serial` link reliability; fixed the `fw_info` field arrangement, a vend session status request bug, and a `vmc_socket` busy/retransmit timeout bug | | 0.0.4.5 | Added semaphore protection on the `tx_buf` reference critical section | | 0.0.4.4 | Aligned with Marshall 3.0: added session status query, an `fw_info` SDK version string field, reader state retrieval, entry type enum, QR e-receipt, and remote vend; added CPU monitoring, a multi-vend product limit to avoid buffer overflow, and additional VMC info fields to `fw_info`; rewrote the sample application | | 0.0.4.3 | Added the ability to start and stop file logging at runtime | | 0.0.4.2 | Fixed a UI event bug | | 0.0.4.1 | Added protection against disabling the reader in idle mode and display event callbacks | | 0.0.4.0 | Added display control support, extra status codes, and the `onStatus` vend callback (see `marshall_t.status_xxxx`) | | 0.0.3.5 | Fixed MSR card encoding | | 0.0.3.4 | Added serial port access protection to `lowlevel_serial_t` and optimized access; changed the vend `onReady` callback to provide the last session object (null on the first call) | | 0.0.3.3 | Fixed an error calling `start_session` from `onReady()` | | 0.0.3.2 | Added the ability to direct SDK logs to a file and the Monyx card to the `card_type` enum; fixed a multi-vend crash from invalid log string formatting and a `get_transaction_id()` bug returning an invalid date inside `onTransactionInfo` | | 0.0.3.1 | Added serial packet dump-level and vend-denied policy parameters, and a `session_timeout` status type on the session class | | 0.0.3.0 | Updated to the latest Marshall protocol revision: link establishment now reports merchant ID, terminal ID, and machine location; added socket MTU and timeout configuration | | 0.0.2.17 | Clarified that the empty-queue error is a notification, not an error | | 0.0.2.16 | Fixed the always-idle bug | | 0.0.2.15 | Updated the `vmc_general` events interface; fixed `reader_always_on` to apply only when always-idle is explicitly disabled | | 0.0.2.14 | Added the ability to enable or disable log output and an always-idle sample | | 0.0.2.13 | Fixed a "stop" issue preventing restart; added `vmc_framework.get_version()` | | 0.0.2.12 | Fixed a critical link bug | | 0.0.2.11 | Added the paymarket machine type; changed the EV-charger machine type | | 0.0.2.10 | Added machine type to configuration and always-idle mode; improved socket handling; fixed a false mismatch-message-ID warning, a fund-available conversion issue, and a machine serial/version/model string length limit | | 0.0.2.9 | Fixed a link bug that sometimes tried to transmit from an empty queue | | 0.0.2.8 | Added parsing of the transfer\_data structure on vend sessions for detailed, readable information | | 0.0.2.7 | Improved socket logging and changed the low-level interface; the `onReady(...)` callback now transfers VPOS configuration; added a `multi_vend_support` flag to `vmc_configuration` (VPOS must be configured for pre-authorization to use multi-vend sessions); fixed a bug preventing some Marshall APIs from being called from `onReady(...)` | | 0.0.2.6 | Unified the vend request API for single and multi-vend, with products declared on `vend_session_t` | | 0.0.2.5 | Added quantity reporting to DCS (requires VPOS 4.0.1.5 rc9 or newer) and a transaction ID report API; fixed session cancel issues after a card is presented but before vend is requested, and when closing a session while the reader is enabled | | 0.0.2.4 | Fixed model/version reporting to DCS; separated the keep-alive timer from the configured timeout | | 0.0.2.3 | Added a log message and link statistics; fixed a buffer-index parsing bug in the middle of the master buffer | | 0.0.2.2 | Fixed a communications issue | | 0.0.2.1 | Fixed a re-transmit timeout that sometimes fired too fast | | 0.0.2.0 | Improved the `low_level_serial` example; added handling for Marshall piggy-back messages; fixed a re-transmit bug | | 0.0.1.9 | Added a VMC auth sample; improved the `low_level_serial` example | | 0.0.1.8 | Fixed a link issue; added CC last-4-digits transfer data | | 0.0.1.7 | Added reader-always-on mode and cash sale | | 0.0.1.6 | Fixed a session close status bug; added a cash sale notification API | | 0.0.1.5 | Added Mifare/mag auth support | | 0.0.1.4 | Added socket support and info session support | | 0.0.1.3 | Initial version |