Allen-Bradley 1746-HT SLC 500 Termination Panel

Configured for high-speed signal distribution in SLC 500 platforms, the Allen-Bradley 1746-HT (1746-HT Termination Panel) provides direct physical and electrical execution of terminal connection management across rack-based I/O configurations.

Hardware Specifications

Backplane Bus Communication and Signal Handling

The 1746-HT utilizes backplane bus communication to interface with the SLC 500 processor. The internal architecture is optimized for high-frequency signal processing, supporting input frequencies up to 250 kHz. Firmare flash compatibility is managed via the rack-based backplane, ensuring that signal timing and step response characteristics remain deterministic within the defined 100 ms input and 2.5 ms output cycles. Proper I/O density scaling requires that the cumulative current draw of the 1746-HT does not exceed the capacity of the SLC 500 power supply in the assigned rack slot.

Frequently Asked Questions

Q: Does the 1746-HT support hot-swapping in an active SLC 500 rack?

A: No. The 1746-HT module must not be removed or inserted while the rack backplane is energized. Power must be removed from the system to prevent electrical damage to the backplane pins or the internal circuitry of the panel.

Q: What is the purpose of the 1746-HCA in relation to this panel?

A: The 1746-HCA is required as a mating cable assembly to complete the I/O connection between the 1746-HT terminal panel and the respective field devices, ensuring mechanical and electrical integrity of the interface.

Field Installation Guidelines

• Rack Mounting: Secure the 1746-HT into the designated SLC 500 rack slot. Ensure the module is properly seated and the chassis screws are tightened to establish a solid electrical connection to the rack ground plane.
• Wiring Termination: Utilize the 1746-HCA cabling system for field I/O connections. Ensure that signal wires are routed away from high-voltage AC lines to prevent crosstalk and inductive interference at high frequencies.
• Shielding: Ground the cable shields at the designated termination point on the cabinet's earth bus to minimize noise pickup. Avoid common-mode ground loops by maintaining a single-point ground reference for the SLC 500 system.
• Frequency Verification: Ensure the field sensors connected to the 1746-HT operate within the 250 kHz frequency limit. Exceeding this limit can result in dropped pulses or incorrect step response timing due to sampling limitations.