The Allen-Bradley 1785-L40B is a powerful PLC-5/40 controller built for medium to large automation tasks. This unit provides 48K words of user memory and handles up to 2048 I/O points. Engineers rely on this processor for its robust communication and flexible I/O configurations.
Product Procurement & Buyer Guide
Matching the 1785-L40B to Your Application
The 1785-L40B excels in systems requiring high I/O counts and multiple networks. You can configure it for 2048 points in any mix. Alternatively, you can use a complementary setup with 2048 inputs and 2048 outputs. This flexibility makes it ideal for complex production lines.
You must mount this controller in a compatible PLC-5 chassis. Suitable models include the 1771-A1B, 1771-A2B, 1771-A3B, 1771-A3B1, and 1771-A4B. The controller draws a backplane current of 3.3A and dissipates 17.3W of power. Use a power supply from the 1771-P4S or 1771-P6S series.
Memory and Backup Options
The standard memory is 48KWords of battery-backed static RAM. The unit uses a 1770-XYC battery to retain your program. For non-volatile backup, you can install an EEPROM memory card. Compatible cards include the 1785-ME16 (16K), 1785-ME32 (32K), 1785-ME64 (64K), and 1785-ME100 (100K). This ensures your logic is safe during power loss.
Communication Capabilities
This processor features four embedded combination ports. Each port can act as a DH+ or a Remote I/O (RIO) adapter or scanner. You can run up to four independent DH+/RIO networks simultaneously. This allows you to connect multiple HMI panels and remote racks. The controller also includes one serial port. This port supports RS-232, RS-423, and RS-422A standards for point-to-point connections.
I/O System Architecture
The 1785-L40B can manage up to 61 total I/O chassis. It supports one local chassis and up to 32 universal remote chassis. You can connect up to 29 PLC-5 racks in total. The I/O scan time per rack varies by baud rate. At 57.6 kbits/s, the scan time is 10 ms. At 115.2 kbits/s, it drops to 7 ms. At 230.4 kbits/s, you achieve a fast 3 ms scan.
Environmental and Power Specifications
This controller operates reliably in temperatures from 0 to 60 degrees Celsius. It can survive non-operating conditions from -40 to 85 degrees Celsius. These tolerances meet strict IEC standards for cold, dry heat, and thermal shock. This makes the unit suitable for demanding industrial environments.
Installation and Wiring Steps
First, install the processor into an empty slot in your 1771 chassis. Ensure you use the correct power supply model. Next, connect your DH+ or RIO cables to the combination ports. Configure each port for its specific network role in your software. Then, connect your serial device to the serial port. Set the DIP switches to match your RS-232 or RS-422A requirements. Finally, apply power and verify the backplane current does not exceed 3.3A.
Logistics & Standard Packaging Details
- One Allen-Bradley 1785-L40B PLC-5/40 Processor Module
- Product documentation and quick reference guide
- Anti-static packaging for safe transport
- We offer express delivery shipping via FedEx, UPS, and DHL.
