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Bill Acceptor Protocols Compared: Pulse, RS232, MDB, ID-003, ccTalk, SSP and More

E&D Trading · Oct 13, 2026

From the E&D Trading technical team: this guide covers Bill Acceptor Protocols Compared: Pulse, RS232, MDB, ID-003, ccTalk, SSP and More. E&D Trading has supplied bill acceptors and parts to the amusement and vending industry for 30 years — call 877-922-6707 if you need help choosing the right part.

A bill acceptor has to tell the machine it is installed in what it just took. The language it uses for that is its protocol (also called the interface). If the protocol does not match the game, vending controller or kiosk, the acceptor may power up and even pull in bills, but the machine will never give credit. This guide compares the protocols you will see in our filters, explains how each one works at the wiring level, and helps you pick the right one. Technical details come from the published standards and manufacturer manuals listed at the bottom of the page.

Contents

Quick comparison

Protocol Type Two-way? Typical machines Main strength Main limit
Pulse Credit pulses on one output line No (inhibit line only) Arcade, amusement, skill/8-liner, car wash, laundry, older vending Simple, universal, easy to wire No status reporting; miscounts if pulse timing is wrong
Serial (RS232 / TTL) Point-to-point serial data Yes Skill games, kiosks, PC-based machines, redemption Reports bill value, escrow, errors Command set differs by brand; voltage levels must match
MDB NAMA multi-drop bus, 9600 baud Yes Vending machines, micro markets, many kiosks Open industry standard; many devices on one bus Built for vending controllers; usually 24V/34V supply
ID-003 JCM serial protocol Yes Casino and gaming machines, kiosks Widely supported in gaming Proprietary command set
ccTalk Open serial bus for coin and bill devices Yes European / UK gaming and AWP, vending, kiosks Open spec, optional encryption, multi-device Less common on U.S. route equipment
SSP / eSSP Innovative Technology serial / USB protocol Yes Gaming, kiosks, ITL validators and recyclers AES-128 encryption in eSSP Mostly limited to ITL hardware
Parallel One output line per denomination No Older and simple controllers Value is known from which line is active Many wires; few denominations
Executive Older vending serial standard Yes Legacy (mainly European) vending Works with older executive-type controllers Largely replaced by MDB
IVS / JPSTD Regional / OEM-specific modes Varies Specific machine builders and markets Drop-in match for those machines Only useful if your machine calls for it

Pulse

What it is: the simplest interface. The acceptor reports a bill by sending a burst of pulses on a credit output, and the machine counts them. Shop Pulse bill acceptors.

How it works: you choose the pulses per dollar with DIP switches or a configuration tool. The Pyramid Apex manual, for example, offers 1 pulse per dollar or 4 pulses per dollar (for quarter-based games), with a fast pulse of 50 ms on / 50 ms off or a slow pulse of 50 ms on / 300 ms off. ICT and other brands offer similar options. The output is usually an open-collector transistor or relay contact, and many acceptors also have an inhibit input so the machine can switch bill acceptance off. Relay outputs can bounce, so Pyramid recommends about a 10 ms software debounce on the host side.

Where it is used: arcade and amusement games, skill and 8-liner boards, coin pushers, car washes, laundry and older vending. Pros: nearly every game board can count pulses, and wiring is simple. Cons: one-way only, so the machine cannot see errors, escrow or bill type; if pulses per dollar or speed do not match the board, credits come out wrong. Brands: ICT, Pyramid Apex, MEI/CPI and most others offer a pulse mode.

Serial (RS232 / TTL)

What it is: a two-way data link between acceptor and host. "Serial" describes the wiring and signal levels; the actual messages depend on the manufacturer's protocol (for example ICT's own protocol, Pyramid's RS232 mode, or JCM ID-003). Shop RS232 bill acceptors.

How it works: the acceptor and host exchange bytes over transmit, receive and ground lines. RS232 uses higher, inverted voltage swings meant for cables to a PC or controller; TTL uses logic-level (typically 5V) signals meant for board-to-board connections. The two are not interchangeable without a level converter. As one example, ICT's published serial protocol runs at 9600 baud, 8 data bits, even parity, 1 stop bit: the acceptor reports a bill in escrow and the controller answers to accept or reject it.

Where it is used: skill games, kiosks, bill breakers, PC-based machines. Pros: the host knows the exact bill, can hold it in escrow, and sees jams, full cashbox and other errors. Cons: both sides must speak the same command set and signal level. Brands: ICT, Pyramid, JCM, ITL, MEI/CPI.

MDB (Multi-Drop Bus)

What it is: the vending industry standard maintained by NAMA (National Automatic Merchandising Association). Shop MDB bill acceptors or 34V MDB models.

How it works: one master, the vending machine controller (VMC), talks to up to 32 peripherals on a shared bus at 9600 baud. Each byte has 8 data bits plus a ninth "mode" bit that marks address versus data. The bill validator answers at its own address (30H), alongside the coin changer, cashless readers and others. The VMC sends commands such as RESET, SETUP, POLL and BILL TYPE, and the validator reports bills, escrow and status. MDB power is commonly 24V or 34V DC supplied by the machine; check your machine's spec.

Where it is used: snack, drink and combo vending, micro markets, and kiosks built on vending controllers. Pros: open standard, plug-compatible across brands, many devices on one harness. Cons: needs an MDB controller, and most arcade or skill boards do not have one. Brands: MEI/CPI VN series, ICT, Pyramid Apex MDB (UB4) models, Coinco and others.

ID-003 (JCM)

What it is: JCM's bidirectional serial protocol, very common in casino and gaming machines. Several other makers offer an ID-003-compatible mode so their units can replace a JCM.

How it works: the controller polls the acceptor with status requests and sends operation and setting commands. Each message is framed with a sync byte, length, command, data and a CRC check. JCM's iVIZION, for example, can be set for RS232 or photo-coupler isolated serial, plus USB and ccTalk options.

Pros: broad support in gaming, rich status and escrow control. Cons: proprietary; the host must be written for it. Brands: JCM (UBA, iVIZION) and compatible modes on other brands. We do not currently have a dedicated ID-003 collection; call us to match a replacement.

ccTalk

What it is: an open serial protocol originally developed by Money Controls for coin and bill devices, widely used in UK and European gaming, amusement-with-prizes (AWP) and vending. Shop ccTalk bill and coin acceptors.

How it works: devices share one serial data line, and each has its own address, so a host can poll coin acceptors, bill validators and hoppers on the same bus. The spec defines a standard command set for bill validators and an optional encryption layer for higher-security devices.

Pros: open, documented, multi-device, optional encryption. Cons: less common on U.S. route equipment. Brands: Money Controls/Crane, ITL, JCM, and many coin acceptors.

SSP / eSSP (Innovative Technology)

What it is: the Smiley Secure Protocol, a serial protocol from Innovative Technology Ltd (ITL). ITL says it was designed to address problems in gaming cash handling such as acceptor swapping, reprogramming and line tapping. eSSP is the encrypted version.

How it works: the host polls the device over serial or USB with CRC-checked packets. In eSSP, a 128-bit AES key is used: half fixed by the machine maker and half negotiated at each power-up using Diffie-Hellman key exchange, so each session uses a different key.

Pros: strong security; supports ITL note recyclers and payout devices. Cons: mostly tied to ITL hardware (NV-series validators and recyclers). See our IT bill acceptors.

Parallel

What it is: instead of counting pulses or sending data, the acceptor activates a separate output line for each bill or channel. Shop parallel interface acceptors.

Pros: very simple logic; the host knows the denomination from which wire went active. Cons: needs a wire per channel and gives no error reporting. Found on some coin acceptors and simpler or older validators.

Executive

What it is: an older vending interface in which the coin mechanism or payment device controls vend credit. It was common on European vending before MDB became the norm. If your machine's controller is labelled "Executive", you need a device set for that mode; otherwise MDB is the modern choice.

IVS and JPSTD

These appear as protocol options on some acceptors for specific machine builders or markets (JPSTD is generally associated with a Japanese-standard interface). They are not general-purpose choices: pick them only if your machine's manual or the original acceptor's label calls for them. Call us with the old part number and we will match it.

SAS, GDS and casino gaming

In casinos you will also see SAS (Slot Accounting System, from IGT) and GDS. SAS is not a bill acceptor protocol: it connects the gaming machine to the casino's accounting host (at 19.2 kbaud) and reports events such as "bill accepted". GDS (Gaming Device Standard) from the Gaming Standards Association is a USB-based protocol between the gaming machine and its peripherals, including note acceptors and printers. In a casino-style machine, the acceptor typically talks to the game by ID-003, GDS, SSP or another serial protocol, and the game reports to the casino by SAS.

How to choose

  1. Match what your machine already uses. Read the label on the old acceptor or the machine manual. The protocol, voltage and harness must all match.
  2. Arcade, amusement, skill or 8-liner board: usually Pulse (set pulses per dollar to match the board) or RS232 if the board supports it.
  3. Vending machine with a VMC: MDB, usually at 24V or 34V.
  4. Kiosk or PC-based machine: RS232, USB or a vendor serial protocol; you want two-way status and escrow.
  5. Casino gaming: ID-003, SSP/eSSP, GDS or ccTalk, depending on the game platform and jurisdiction.
  6. Check voltage. Browse by voltage: 12V, 110V, 34V MDB, or see Shop by Protocol.

FAQ

Can one bill acceptor do more than one protocol?

Often, yes. Many ICT and Pyramid units switch between pulse and serial with DIP switches or a configuration card, and JCM's iVIZION supports several interfaces. MDB units are usually a separate model with a different harness and supply voltage.

Is RS232 the same as TTL serial?

No. They can carry the same messages, but the voltage levels differ. Connecting one to the other without a converter can stop communication or damage hardware.

My machine gives the wrong credit for a $1 bill. Why?

On pulse machines this is almost always a pulses-per-dollar or pulse-speed mismatch. Set the acceptor to match the board (for example 1 or 4 pulses per dollar, fast or slow pulse), then power-cycle it.

Is MDB only for vending?

It was designed for vending, but many kiosks and micro markets use MDB controllers too.

Which protocol is most secure?

Protocols with encryption, such as ITL's eSSP and ccTalk's encryption option, are designed to resist tampering. Pulse has no security on the line itself.

Can you set up my acceptor before it ships?

As an authorized service center for ICT, Pyramid and MEI/CPI, we can help configure and match units. Call 877-922-6707 or use the chat on this page.

Sources

Need help? Call E&D Trading at 877-922-6707 or email orders@endtrading.com. Most parts mentioned here ship from our Hollywood, FL warehouse.

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