OPTO 22 SNAP-PAC Series Modules SNAP-PAC-S1

Technical Dossier

Product Details And Specifications

OPTO 22 SNAP-PAC Series Technical Notes

The Evolution of SNAP-PAC Architecture

The SNAP-PAC series succeeded OPTO 22's earlier SNAP Ultimate and SNAP Ethernet I/O platforms, which used a separate controller-plus-brain architecture. The SNAP-PAC line consolidated control intelligence directly into the controller module, eliminating the need for a separate SNAP Ethernet Brain on standalone racks. Early SNAP-PAC controllers (circa 2004–2008) operated on 10/100 Ethernet and supported serial legacy protocols including Modbus RTU and DNP3. Mid-generation revisions introduced dual Ethernet ports for network redundancy and expanded memory capacity to support larger PAC Control strategy files. The SNAP-PAC-S1 and SNAP-PAC-S2 represent the standalone controller tier, while the SNAP-PAC-R1 and SNAP-PAC-R2 serve as rack-mounted variants designed for SNAP-PAC mounting racks. The SNAP-PAC-EB1 and SNAP-PAC-EB2 Ethernet brains extend I/O to remote racks without a local controller. As of 2020, OPTO 22 introduced the groov EPIC (GRV-EPIC-PR1) as the next-generation successor platform, offering Linux-based edge computing, Node-RED integration, and OPC UA native support. Facilities running SNAP-PAC hardware face a compatibility boundary: groov EPIC does not share the same backplane or I/O modules, requiring a full rack migration rather than a drop-in upgrade. This architectural discontinuity has extended the active service life of SNAP-PAC installations, as many operators defer migration due to capital cost and process risk.

SNAP-PAC Full Catalog & Functionalities (SKU List)

Controllers — Standalone

• SNAP-PAC-S1: Standalone PAC, single Ethernet port, 256 MB RAM, USB programming port, supports up to 512 I/O points on local rack.
• SNAP-PAC-S2: Standalone PAC, dual Ethernet ports, 512 MB RAM, enhanced strategy file capacity, supports redundant network topologies.

Controllers — Rack-Mounted

• SNAP-PAC-R1: Rack-mounted PAC controller, single Ethernet, mounts in SNAP-PAC-RCK4/RCK8/RCK16 racks, local I/O only.
• SNAP-PAC-R2: Rack-mounted PAC controller, dual Ethernet, expanded memory, supports peer-to-peer communication with other SNAP-PAC units.

Ethernet Brains (Remote I/O Expansion)

• SNAP-PAC-EB1: Single-port Ethernet brain for remote SNAP-PAC racks; controlled by a SNAP-PAC-S or R series controller.
• SNAP-PAC-EB2: Dual-port Ethernet brain for remote racks; supports daisy-chain and star network topologies.

Analog Input Modules

• SNAP-AIMA-4: 4-channel analog input, 4–20 mA, 16-bit resolution, field-configurable range.
• SNAP-AIV-4: 4-channel analog voltage input, ±10 VDC, 16-bit resolution.
• SNAP-AITM-2: 2-channel thermocouple input module, supports J, K, T, E, R, S, B types.
• SNAP-AIRTD-8: 8-channel RTD input, supports PT100/PT1000, 3-wire configuration.

Analog Output Modules

• SNAP-AOMA-4: 4-channel analog current output, 4–20 mA, 16-bit DAC, loop-powered.
• SNAP-AOV-5: 4-channel analog voltage output, 0–10 VDC / ±10 VDC selectable.

Digital Input Modules

• SNAP-IDC5: 4-channel DC digital input, 5–28 VDC, optically isolated, 1 ms response time.
• SNAP-IAC5A: 4-channel AC digital input, 85–250 VAC, optically isolated.

Digital Output Modules

• SNAP-ODC5SRC: 4-channel DC sourcing digital output, 5–28 VDC, 0.5 A per channel, solid-state.
• SNAP-OAC5A: 4-channel AC digital output, 24–280 VAC, solid-state relay, zero-crossing switching.

Communication & Serial Modules

• SNAP-SCM-232: RS-232 serial communication module, supports Modbus RTU master/slave, ASCII protocols.
• SNAP-SCM-485-422: RS-485/RS-422 serial module, multi-drop bus support, up to 32 nodes.

Power Supplies

• SNAP-PS5: 5 VDC rack power supply, 3 A output, mounts in SNAP-PAC rack power slot.
• SNAP-PS24: 24 VDC auxiliary power supply module for field device power distribution.

Mounting Racks

• SNAP-PAC-RCK4: 4-slot SNAP-PAC mounting rack, DIN-rail or panel mount.
• SNAP-PAC-RCK8: 8-slot SNAP-PAC mounting rack.
• SNAP-PAC-RCK16: 16-slot SNAP-PAC mounting rack, maximum I/O density per rack.

Quality Control for the SNAP-PAC Range

SNAP-PAC modules present specific test challenges due to their integrated backplane bus architecture and Ethernet-dependent I/O scanning. DriveKNMS applies the following verification protocol to all SNAP-PAC inventory prior to dispatch:

• Backplane continuity test: Each module is seated in a reference SNAP-PAC rack and scanned for correct backplane register mapping. Modules that fail to enumerate correctly are quarantined regardless of visual condition.
• Ethernet brain handshake verification: For EB1/EB2 brains and R-series controllers, a PAC Control strategy is loaded and I/O point read/write cycles are executed across all populated module slots to confirm bus integrity.
• Analog calibration check: All analog input and output modules are tested against NIST-traceable reference signals. Modules with drift exceeding ±0.1% of full scale are recalibrated or rejected.
• Firmware revision logging: Controller firmware version is recorded and disclosed in the shipment documentation. Customers are advised of any firmware delta relative to their installed base to allow pre-deployment update planning.
• Thermal cycling: Modules destined for high-ambient installations (refineries, compressor stations) undergo a 4-hour thermal soak at 55°C prior to final inspection.