Technical Specifications
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Manufacturer: Allen Bradley (Rockwell Automation)
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Part Number: 1785-L40B
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Product Type: PLC-5/40 CPU Module
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Memory: 48K words SRAM
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Program Backup: EEPROM (removable)
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I/O Capacity:
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Up to 2048 analog I/O
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Up to 32,000 total digital I/O
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Communication Ports:
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4 channels configurable as DH+ or Remote I/O
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Instruction Execution Speed: 2 ms per 1K boolean instructions
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Compatible Chassis: 1771 series
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Expansion: Supports multiple chassis via remote I/O or control networks
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Power Requirements: Supplied by chassis power supply (e.g., 1771-P7)
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Programming Software: RSLogix 5
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Battery Backed RAM: Yes
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Operating Temperature: 0°C to 60°C (32°F to 140°F)
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Mounting: Installed in 1771 chassis
Key Features
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48K word SRAM memory with EEPROM backup for program retention
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Supports up to 2048 analog I/O points and 32,000 digital I/O points
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Four configurable channels supporting DH+ or Remote I/O communication
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Modular design for scalable control systems using 1771 I/O platform
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Compatible with legacy PLC-5 architectures, ideal for retrofit and expansion
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High-speed instruction execution suitable for demanding industrial applications
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Non-volatile EEPROM storage ensures program retention during power loss
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Supports redundant communication and distributed control configurations
Compatible Components & Accessories
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I/O Chassis: Allen Bradley 1771 Series (e.g., 1771-A1B, 1771-A4B)
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Power Supplies: 1771-P7, 1771-P6S
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Communication Interfaces: DH+, RIO adapters, and bridges
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Programming Software: RSLogix 5
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Backup Modules: 1785-ME16, 1785-ME32 EEPROM modules
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I/O Modules: 1771 series discrete and analog input/output modules
Industry Applications
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Manufacturing and process automation
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Water treatment and wastewater facilities
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Oil, gas, and petrochemical control systems
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Power generation and distribution infrastructure
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Automotive and assembly lines
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Pulp and paper processing plants
Installation & Maintenance Notes
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Install only in a compatible 1771 I/O chassis with appropriate power supply
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Configure DH+/RIO channels via jumpers or software as needed for system architecture
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EEPROM module must be inserted prior to power-up for program restoration
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Ground chassis properly and follow industrial wiring best practices
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Periodically verify memory integrity and battery condition for long-term system stability
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Use RSLogix 5 for all program development, documentation, and diagnostics
Description
1785L40B
PLC CPU Module
48K Word SRAM
PLC-5/40
2048 Analog I/O
4 DH+/Remote I/O Channels
EEPROM Program Backup
Specifications
| Manufacturer | Rockwell Automation |
| Power Supply: | 1771-P4S, 1771-P6S, 1771-P4S1, 1771-P6S1 |
| Memory: | 48 KWords |
| Battery: | 1770-XYC |
| Maximum number of I/O per link: | 32 |
| Operating Temperature: | EC 60068-2-1 (Test Ad, Operating Cold), IEC 60068-2-2 (Test Bd, Operating Dry Heat), IEC 60068-2-14 (Test Nb, Operating Thermal Shock): 0…60 o C (32…140 o F) |
| Non-Operating Temperature: | IEC 60068-2-1 (Test Ab, Un-packaged Nonoperating Cold), IEC 60068-2-2 (Test Bc, Un-packaged Nonoperating Dry Heat), IEC 60068-2-14 (Test Na, Un- packaged Nonoperating Thermal Shock): –40…85 o C (– 40…185 o F) |
| Brand | Allen-Bradley |
| Embedded Communication interfaces: | 4 DH+/Remote I/O (Adapter or Scanner) 1 serial port, configurable for RS-232 and 423 and RS-422A standards |
| Backplane current load: | 3.3A |
| Power Dissipation: | 17.3W |
| Product Type: | Programmable Logic Controller |
| Part Number/Catalog No. | 1785-L40B |
| Product Family: | PLC5 |
| Module Type | Standard Processor |
| Processor | PLC-5/40 |
| Max User Memory Words | 48 Kilowords |
| Battery-Backed Static RAM | Yes |
| EEPROM Program Backup Option (using 1785-ME16, -ME32, -ME64, and -M100) | Yes |
| Protected Memory | No |
| Max Total I/O | 2048 (any mix) or 2048 in + 2048 out (complementary) |
| Max Analog I/O | 2048 |
| I/O Scan Time Per Rack | 10 ms at 57.6 kbits/s, 7 ms at 115.2 kbits/s, 3 ms at 230.4 mbits/s |
| Max I/O Chassis Extended Local | 0 |
| Max I/O Chassis Total | 61 |
| Max I/O Chassis Universal Remote | 32 Max. Per I/O Link |
| RS-232-C/422-A/423- A Ports | 1 |
| Control Coprocessor Expansion Port | Yes |
| UPC | 10612598124012 |
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