The expansion DAQ devices communicate with the base devices via RS-485 (Modbus RTU) via convenient RJ45 feed-through connectors and CAT5e cabling. Devices can be co-located in a stack or distributed throughout your facility up to 4,000 feet away.
| Model | Description |
| 410N | 16 Optically Isolated Input / 16 Reed Relay Output SeaI/O Expansion Module |
| 420N | 16 Optically Isolated Input / 8 Form C Relay Output SeaI/O Expansion Module |
| 430N | 32 Optically Isolated Input SeaI/O Expansion Module |
| 440N | 32 Reed Relay Output SeaI/O Expansion Module |
| 450N | 16 Form C Relay Output SeaI/O Expansion Module |
| 450N-OEM | 16 Form C Relay Output SeaI/O Expansion Module |
| 462N | 96 Channel TTL Digital Interface SeaI/O Expansion Module |
| 462N-KT | 96 Channel TTL Digital Interface SeaI/O Expansion Module Kit - 462N + (2) CA237 Cables |
| 463N | 96 Channel TTL Digital Interface SeaI/O Expansion Module |
| 470N | 16 A/D, 2 D/A, 8 Open-Collector Outputs, 8 Isolated Inputs SeaI/O Expansion Module |
| 520N | 8 Optically Isolated Input / 8 High-Current Form C Relay Output SeaI/O Expansion Module |
| 530N | 16 Optically Isolated Input / 16 Open-Collector Output SeaI/O Expansion Module |
| 540N | 32 Open-Collector Output SeaI/O Expansion Module |
| 570N | 8 16-bit A/D, 8 Isolated Inputs, 8 Form C Relay Outputs SeaI/O Expansion Module |