Configured for single-axis closed-loop servo positioning in SLC 500 local I/O chassis, the Allen-Bradley 1746-HS (also referenced as 1746-HS IMC 110 Motion Controller Module) decodes 24 VDC quadrature encoder feedback at up to 300 kHz and executes motion profiles independent of processor scan.

Catalog Identity

The 1746-HS is the base catalog number for the IMC 110 motion controller. The /A revision denotes the initial hardware issue. No further dash-suffix options were released by Rockwell Automation. Module is discontinued; spares trade as 1746HS or 1746-HS/A.

Hardware Specifications

Backplane Bus Execution & Firmware Lock

The 1746-HS exchanges motion data with the SLC 500 processor over the 1746 parallel backplane using block-transfer registers mapped into M-file data tables. Motion trajectory calculation runs on the module's onboard logic, not in the processor scan cycle, so position loop closure is unaffected by ladder program execution time. No field-flashable firmware exists; the IMC 110 instruction set is fixed per hardware revision. I/O density is one axis per single slot, with no daisy-chain expansion on the same module. Place the card in the slot nearest the CPU to keep backplane transaction latency minimal.

Ordering Information

• 1 x 1746-HS IMC 110 Motion Controller Module
• 1 x Printed installation and wiring insert

Chassis Integration Notes

• Slot Position: Mount adjacent to the processor module; avoid remote I/O adapter chassis.
• Encoder Wiring: Use shielded twisted pair for A, B, Z lines; terminate shield at the module end only to system ground.
• Power Budget: Sum 300 mA at 5 VDC plus 104 mA at 24 VDC against the 1746 chassis power supply derating curve before commissioning.
• Isolation Boundary: The user-side 5 VDC rail (150 mA) is galvanically isolated from backplane logic; do not tie user encoder supply to backplane 5 VDC.

Frequently Asked Questions

Is the 1746-HS hot-swappable on a powered SLC 500 chassis?

No. Power down the chassis before insertion or removal. Engaging the backplane connector under live 5 VDC can arc the edge fingers and corrupt the processor I/O image table.

What processors support the IMC 110 instruction set?

SLC 5/03, 5/04 and 5/05 CPUs with the motion option enabled recognize the module. SLC 5/01 and 5/02 lack the block-transfer bandwidth for closed-loop servo updates.

Can 5 VDC differential encoders be wired to this 24 VDC input module?

Direct 5 VDC differential signals are out of the 24 VDC input threshold. Use an external line driver or a 1746-HSRV instead if the feedback device is 5 VDC TTL.

How is the 300 kHz input frequency affected by quadrature error?

At 0 deg phase error on A/B the module locks up to 300 kHz. Phase skew beyond quadrature tolerance reduces the maximum trackable frequency and may double-count; verify encoder cable length against capacitive roll-off.

Does the module retain position after a backplane power cycle?

No. The 1746-HS does not hold absolute position across power loss. The CPU must re-home or preset the axis via M-file commands on restart.

What is the isolated user-side 5 VDC 150 mA rail for?

It powers the encoder interface side isolated from backplane logic to suppress ground-loop noise from long cable runs to the motor feedback device.

Can two 1746-HS modules synchronize for gearing?

No inter-module camming exists on 1746-HS. Multi-axis coordination requires a 1756 or 1769 Logix platform with Kinetix drives.

What happens when the 15 VDC aux rails exceed 30 mA or 200 mA?

Exceeding either 15 VDC auxiliary draw forces the module into a fault state and de-energizes the position loop. Size external encoder splitters accordingly.