MDB Parameter Explanations (Nayax)
These settings relate to how the Nayax reader communicates with the vending machine controller (VMC) over MDB — Multi-Drop Bus, the vending industry’s standard communication protocol.
Think of MDB as the “language” between the machine and the payment device.
MDB 98 — Cashless MDB Address
Sets which MDB address the Nayax device uses.
- 0 = Cashless Device #1 (standard)
Some machines allow two cashless devices; #1 is the default.
MDB 170 — Enable Fiscalization (FTL)
Enables “Fiscalization,” meaning the device formats data according to certain tax or reporting standards used in specific countries.
If you’re not in an FTL-required region, this stays off.
MDB 172 — Send "End Session" After "Session Complete"
Controls communication sequencing:
- If enabled, Nayax sends an extra “End Session” command after the machine reports “Session Complete.”
This is usually for machines that require stricter closure of the transaction loop.
MDB 174 — FTL Mode
Another fiscalization parameter. Defines which fiscal-logging protocol to use when 170 is enabled.
MDB 524 — Maximum Response Time
How long (ms) Nayax waits for a vending-machine reply before assuming communication failure.
- 90 ms is typical.
MDB 606 — Age Verification Timeout
Used for machines that require age confirmation (e.g., tobacco). Time limit before verification is considered failed.
Often not used.
MDB 610 — Ignore Start State
If enabled, Nayax starts communication even if the VMC doesn’t send a proper initialization (“Start”) signal.
Useful for older machines with strange MDB behavior.
MDB 611 — Ignore VMC Configuration
If 1, Nayax ignores some configuration details sent by the machine.
Used when the machine sends incomplete or incorrect configuration frames.
MDB 612 — Poll IRQ Timeout (ms)
How long Nayax waits for machine “interrupt” messages during polling cycles.
- Default 500 ms.
MDB 613 — Vend Result Timeout
Maximum time (seconds) Nayax waits for the machine to report vend success or vend failure after payment is authorized.
- 90 seconds is typical.
If the machine never reports back, the sale may be canceled or flagged.
MDB 614 — Session Complete Timeout (ms)
How long Nayax waits for the machine to confirm a session was completed.
- Default 500 ms.
MDB 615 — MDB Rx Timeout
Maximum time Nayax waits for any MDB inbound message.
- Usually 60 seconds.
MDB 616 — Post Cash Sale Timeout
Delay after a cash sale before five-cent polling resumes.
Mostly unused in cashless configurations.
MDB 618 — MDB Communication Time Delay
Additional delay inserted between MDB messages.
Used for compatibility with older or slow VMCs.
MDB 620 — Disable Sending Cash Sale Notification
Controls how cash sales are reported:
- 0 — Nayax reports cash sales to its backend.
- 1 — Nayax stops reporting cash sales.
MDB 621 — MDB Flags
Bitmask of special behaviors. Value 6 (binary 00000110) means:
- Ignore Messages
- Pre-Selection Mode
Pre-Selection Mode: allows the consumer to select a product before payment.
MDB 625 — MDB Custom Config
Reserved for advanced/engineering overrides. Usually unused.
MDB 630 — Poll Stop Event Timeout
Time (seconds) Nayax waits after polling stop before resetting.
- 90 seconds default.
MDB 640 — Reader State Error Event Timeout
How long Nayax waits before reporting a “Reader State Error.”
- 90 seconds default.
MDB 940 — MDB Level 3 Optional Features
Enables advanced MDB features (part of Level 3 of the MDB spec).
Value 32 normally means “consumer interface extensions” like bonus features or advanced pricing, depending on exact bitmask definitions.
Nayax Error Codes and Solutions for Smart Vending on MDB Protocol
Stop Nayax errors on your AI Smart Cooler or Vending Machine! This guide targets the Nayax VPOS Touch and AI Smart Coolers. Learn the pre-authorization secrets you need to know to fix declines and unlock your profits.
AI Smart Coolers usually rely on a pre-authorization payment flow or incremental pre-authorization. ReyVend offers both options but recommends incremental pre-authorization for increased sales and a better consumer experience. The core difference between standard pre-authorization and incremental pre-authorization—the two payment flows used by AI Smart Coolers—is determined by how the customer's funds are secured and held.