OPTO 22 SNAP Series Modules

Technical Dossier

Product Details And Specifications

OPTO 22 SNAP Series: Comprehensive Module Range and Technical Overview

The OPTO 22 SNAP (Simple Networking and Automation Platform) series represents one of the most widely deployed modular I/O architectures in global heavy industry. Installed across petrochemical refineries, nuclear power generation facilities, offshore platforms, and large-scale chemical processing plants, SNAP hardware is recognized for its deterministic signal conditioning, open-protocol communication, and field-replaceable module design. The platform's distributed I/O topology allows control engineers to position signal acquisition points at the process level, reducing wiring runs and improving noise immunity in high-EMI environments. SNAP systems are found in both standalone PAC (Programmable Automation Controller) configurations and as remote I/O nodes integrated into third-party DCS and SCADA architectures via OPC-UA, Modbus TCP, and PROFINET adapters.

The Evolution of SNAP Architecture

The SNAP platform was introduced by OPTO 22 in the mid-1990s as a successor to its earlier G4 and Pamux I/O families. The original SNAP architecture used a parallel backplane bus with dedicated mounting racks (SNAP-B series) and relied on analog and discrete signal modules communicating through a local processor brain. Early brain modules such as the SNAP-LCE and SNAP-LCSX provided serial and Ethernet connectivity respectively, establishing the foundation for network-distributed I/O.

The second architectural generation introduced the SNAP PAC family — SNAP-PAC-R1, SNAP-PAC-R2, SNAP-PAC-S1, SNAP-PAC-S2 — which unified the controller and I/O brain into a single programmable unit running the groov EPIC firmware stack. This generation added IEC 61131-3 programming compliance, RESTful API access, and MQTT/Sparkplug B support, enabling direct integration with cloud-based SCADA and IIoT platforms without middleware.

Compatibility considerations are significant across generations: original SNAP mounting racks (SNAP-B series) are physically and electrically compatible with both legacy brain modules and current PAC brains, preserving installed-base investments. However, SNAP-LCE and SNAP-LCSX brains are no longer manufactured and require lifecycle sourcing from specialist distributors. Signal modules (analog, discrete, serial) maintain backward compatibility across all rack generations, making module-level replacement straightforward even in mixed-generation installations.

SNAP Full Catalog & Functionalities (SKU List)

The following SKUs represent the core SNAP series module range, organized by functional category. Each entry reflects a verified, commercially documented part number within the OPTO 22 SNAP product family.

Power Supplies

• SNAP-PS5: 5 VDC rack power supply, 4A output, mounts directly to SNAP mounting rack, powers backplane bus for up to 16 I/O modules.
• SNAP-PS5U: Universal input (85–264 VAC) 5 VDC power supply, UL/CE listed, designed for international installations with variable mains voltage.

Mounting Racks

• SNAP-B4: 4-module SNAP mounting rack, DIN-rail or panel mount, compatible with all SNAP brain and I/O modules.
• SNAP-B8: 8-module SNAP mounting rack, standard density configuration for mid-scale I/O nodes.
• SNAP-B16: 16-module SNAP mounting rack, maximum density per rack, used in high-channel-count applications.

Brain / Controller Modules

• SNAP-PAC-R1: Rack-mount PAC brain, single Ethernet port, 100 Mbps, runs groov PAC firmware, supports Modbus TCP and OPTO 22 native protocol.
• SNAP-PAC-R2: Rack-mount PAC brain, dual Ethernet ports, supports redundant network topologies, enhanced memory for large I/O maps.
• SNAP-PAC-S1: Standalone PAC controller with integrated I/O rack, single Ethernet, suitable for standalone machine control.
• SNAP-PAC-S2: Standalone PAC controller, dual Ethernet, expanded program memory, supports peer-to-peer communication with other PAC units.
• SNAP-LCE: Legacy Ethernet brain module (discontinued), 10 Mbps, used in early SNAP Ethernet I/O nodes; requires lifecycle sourcing.

Analog Input Modules

• SNAP-AIMA-4: 4-channel analog input, 4–20 mA, 12-bit resolution, for current loop process signals (pressure, flow, level transmitters).
• SNAP-AIV: Single-channel analog voltage input, ±10 VDC range, 12-bit, for voltage-output sensors and transducers.
• SNAP-AITM-2: 2-channel thermocouple input module, supports J, K, T, E, R, S, B type thermocouples, cold-junction compensated.
• SNAP-AIRTD: RTD input module, supports PT100 and PT1000, 3-wire configuration, for precision temperature measurement in process environments.

Analog Output Modules

• SNAP-AOA-23: 2-channel analog output, 4–20 mA, 12-bit, for driving control valves, variable speed drives, and positioners.
• SNAP-AOV-25: 2-channel analog voltage output, 0–10 VDC, 12-bit, for setpoint signals to process controllers and actuators.

Discrete I/O Modules

• SNAP-IDC5: 4-channel DC discrete input, 5 VDC logic level, for TTL and low-voltage digital signals from PLCs and encoders.
• SNAP-IAC5A: 4-channel AC discrete input, 90–140 VAC, optically isolated, for field-level AC status signals.
• SNAP-OAC5A: 4-channel AC discrete output, triac-based, 12–140 VAC, 0.5A per channel, for AC load switching.
• SNAP-ODC5SRC: 4-channel DC discrete output, sourcing type, 5–60 VDC, 0.5A per channel, for DC actuator and relay coil control.

Sourcing Hard-to-Find & Obsolete SNAP Parts

The SNAP series spans over three decades of production. A significant portion of the installed base — particularly systems using SNAP-LCE, SNAP-LCSX, and first-generation SNAP-B rack variants — operates on hardware that OPTO 22 no longer manufactures. End-of-life designation does not eliminate operational demand; process industries routinely maintain equipment for 20–30 year lifecycles, and unplanned downtime caused by unavailable spare parts carries costs that far exceed the procurement price of the module itself.

DriveKNMS maintains a dedicated inventory of SNAP series modules sourced through authorized secondary market channels, including tested surplus, decommissioned plant equipment, and OEM overstock. All units undergo functional verification before dispatch. For discontinued brain modules (SNAP-LCE, SNAP-LCSX) and legacy power supplies (SNAP-PS5, SNAP-PS5U), DriveKNMS provides documented test reports and 12-month operational warranties. Customers operating mixed-generation SNAP installations can submit complete BOM lists for consolidated sourcing, reducing procurement lead time and logistics complexity.

Quality Control for the SNAP Range

SNAP modules present specific test challenges due to their backplane bus architecture and optically isolated signal paths. DriveKNMS applies a structured verification protocol to all SNAP inventory:

• Backplane bus continuity test: Each module is seated in a reference SNAP-B8 rack and bus communication integrity is verified at 5 VDC nominal and ±5% voltage tolerance limits.
• Power supply load test: SNAP-PS5 and SNAP-PS5U units are tested under full rated load (4A continuous) for a minimum of 30 minutes. Output ripple and regulation are measured against OPTO 22 published specifications.
• Analog signal accuracy verification: Analog input and output modules are calibrated against a traceable reference standard. Linearity error, offset, and gain are recorded for each channel.
• Discrete channel isolation test: Optical isolation integrity is verified at 1500 VAC for 1 minute per channel group, confirming that field-side faults cannot propagate to the logic bus.
• Firmware and communication handshake: Brain modules (SNAP-PAC-R1, SNAP-PAC-R2, SNAP-PAC-S1, SNAP-PAC-S2) are powered and queried via Ethernet to confirm firmware version, IP stack response, and I/O map accessibility prior to shipment.