Allen-Bradley 1785-LT/B PLC-5 Classic Programmable Controller Module
$123.00
$320.00
Description
Allen-Bradley 1785-LT/B PLC-5 Classic Programmable Controller Module
The Allen-Bradley 1785-LT/B, also cataloged as the 1785-LT programmable controller module, operates as a dedicated hardware component for centralized logic processing and network orchestration within 1771 I/O chassis architecture. Designed for insertion into the left-most slot of a 1771 chassis, this controller executes digital discrete instructions, analog data processing, and industrial communications via Data Highway Plus (DH+) and RS-232-C/422-A/423-A serial links without relying on external coprocessing hardware.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 1785-LT/B |
| Brand | Allen-Bradley |
| Origin | USA |
| Weight | 1.4 kg |
| Dimensions | 5.1 cm x 27.9 cm x 15.2 cm |
| Operating Temp | 0 to 60 deg C |
| Power Consumption | Backplane load current dependent on 1771 chassis supply |
| Embedded Memory | 6K words SRAM |
| Memory Expansion | Up to 14K words (1785-MR 4K RAM, 1785-MS 8K RAM, 1785-MJ 8K EEPROM) |
| Program Scan Time | 2 ms per K words (bit logic), 8 ms per K words (typical application) |
| I/O Capacity | 512 inputs + 512 outputs (max 3072 points any mix, 512 analog channels) |
| Chassis Rack Support | Local: Up to 4 racks (1 resident); Remote: Up to 3 racks |
| Communication Ports | 1x DH+ channel, RS-232-C / RS-422-A / RS-423-A serial, Control Coprocessor port |
| DH+ Scan Time per Rack | 10 ms at 57.6 kbit/s, 7 ms at 115.2 kbit/s, 3 ms at 230.4 kbit/s |
| Relative Humidity | 5 to 95% non-condensing |
| Shock Resistance | 30G |
Backplane Bus Dynamics & Firmware Synchronization
The 1785-LT/B interfaces directly with the 1771 backplane bus to maintain high-velocity execution of local I/O cycles and control coprocessor transactions. Firmware flash compatibility ensures synchronized deterministic instruction timing across legacy 1771 I/O modules, preventing backplane bus contention during high-density I/O scan sequences. Network throughput scales dynamically across the DH+ medium based on configured baud rates, isolating serial handshake latencies from real-time ladder execution cycles.
Frequently Asked Questions
Q: What is the backplane slot requirement for installing the 1785-LT/B module?
A: The 1785-LT/B controller must be installed exclusively in the left-most slot (Slot 0) of a compatible 1771 I/O chassis to properly interface with backplane power lines and local I/O bus lines.
Q: Can memory be upgraded beyond the 6K words embedded SRAM onboard?
A: Yes, total memory capacity can be expanded up to 14K words by installing optional memory modules, including the 1785-MR (4K RAM), 1785-MS (8K RAM), or 1785-MJ (8K EEPROM).
Q: What are the communication scan rates for remote I/O racks connected via DH+?
A: The scan time per remote rack varies with the selected transmission rate: 10 ms at 57.6 kbit/s, 7 ms at 115.2 kbit/s, and 3 ms at 230.4 kbit/s.
Field Installation Guidelines
Ensure the 1771 chassis power supply is completely de-energized prior to inserting or removing the 1785-LT/B controller module to prevent backplane edge connector damage. Seat the module firmly into the left-most slot of the chassis until the top and bottom card guides lock securely into position. Maintain proper grounding by connecting the chassis grounding stud directly to the central enclosure earth ground bus using low-impedance copper conductor. Maintain physical isolation between communication cables (DH+ trunk, RS-232/422 serial lines) and high-voltage AC power wiring to prevent inductive noise coupling.
Features
Minimum Order Quantity (MOQ)
We welcome bulk orders and have a minimum order quantity of just one unit.
Certificates and Documentation
Upon request, we can provide all necessary documentation, including Certificates of Origin/Conformance and other required export documents.
Delivery Time
For items in stock, we aim to deliver within 1-3 days after payment confirmation. Items with specified lead times will be delivered according to the quoted schedule.
Payment Methods
We accept 100% T/T (Telegraphic Transfer) payment before shipping. For items with lead times, a 30% deposit is required upfront, with the remaining 70% due before shipment. For RMB transfers, please contact us if you have an agent in China.
Warranty
We offer a standard one-year warranty on all new and original items. If you require an extended warranty, please contact us for additional cost details.
Refund and Return Policy
Your satisfaction is important to us. If you need to return an item, it must be done within 30 days of the order date. The product must be unused, unopened, and in its original packaging with all accessories included. Refunds are processed within 5-7 business days after we receive the returned item. Please note that shipping and related charges are non-refundable.
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