When a Legacy RIO Network Blocks Your ControlLogix Upgrade
A plant engineer faced a familiar problem: the ControlLogix processor was ready, but dozens of legacy Remote I/O racks still needed to communicate with it. Ripping out the old network meant weeks of downtime. The Allen-Bradley 1756-RIO solved it in a single slot.
This ControlLogix Remote I/O communication module connects a ControlLogix processor directly to an existing RIO network. It works as either a scanner or an adapter, so you can integrate legacy racks without replacing them. The module ships in default scanner mode.
What the 1756-RIO Does in Your System
As a scanner with one RIO port, the 1756-RIO supports up to 32 physical racks (0…76) in any partial rack combination. It handles all remote I/O baud rates and automatically updates block transfers at every possible location. Analog and specialty data move without message instructions, which simplifies programming.
Switch it to adapter mode and the module lets your ControlLogix controller monitor or exchange data with an existing system scanner. It also sends messages to other controllers on the RIO network. For HMI and SCADA integration, the module works through Allen-Bradley communication cards.
Key Specifications at a Glance
| Parameter | Value |
|---|---|
| Module Type | Remote I/O Adapter Module |
| Series | ControlLogix |
| RIO Ports | One (1) |
| Physical Racks | 32 (0…76), any combination |
| Backplane Current (5.1 V DC) | 450 milliamps |
| Backplane Current (24 V DC) | 5 milliamps |
| Isolation Voltage | 50 Volts Continuous |
| Operating Temperature | 32–140 °F (0–60 °C) |
| Dimensions | 5.51 x 4.41 x 5.71 inches |
| Wire Size | 20 AWG |
| Enclosure | None |
| Location | Chassis |
The 1756-RIO draws 450 mA at 5.1 V DC and 5 mA at 24 V DC from the backplane. It provides 50 V continuous isolation with basic insulation from RIO communication lines to the backplane, type tested at 500 V AC for 60 seconds. The physical RIO connection uses 1771-CD or Belden 9463 (Blue Hose) cable.
Where This Module Fits
Legacy system migration. Instead of replacing every remote rack, the 1756-RIO bridges your ControlLogix processor to the existing RIO network. This preserves field wiring and cuts migration cost dramatically.
SCADA and HMI data flow. The module transports analog and specialty data to supervisory systems through Allen-Bradley communication cards, keeping operators informed without added message instructions.
Redundant topology. The 1756-RIO supports simplex and redundant controller configurations. Compatible standard power supplies include 1756-PA72/C, 1756-PA75/B, 1756-PB72/C, 1756-PB75/B, 1756-PC75/B, and 1756-PH75/B. Redundant options include 1756-PA75R, 1756-PB75R, and 1756-PSCA2.
Installation Notes
The 1756-RIO is a single-slot module that installs in any slot of any ControlLogix chassis, including 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17. Turn off chassis power before installation to prevent electrical arcing. Multiple 1756-RIO modules can share one chassis; the number depends on your power supply rating.
When wiring into an RIO network, confirm your cable type and any required connection hardware with your supplier. The 1771-CD or Belden 9463 (Blue Hose) cable is specified for this connection.
Sourcing the 1756-RIO
Oil AutoTech supplies the 1756-RIO as a ready-to-ship spare for oil, gas, and industrial automation applications. Fast dispatch, worldwide delivery, and hands-on technical selection help keep your project on schedule. Please verify current lifecycle status and availability with Oil AutoTech before ordering.
Contact Oil AutoTech today for pricing and availability.
