1771-IC – Allen-Bradley PLC 5 Digital DC Input Module
Product at a Glance
The 1771-IC is an 8-channel digital DC input module for Allen-Bradley PLC 5 systems. It operates on 42-56 VDC and sinks current from source loads. Built-in input filtering suppresses noise and contact bounce. This reduces electrical downtime and extends product life. The module ships in an anti-static bag for ESD protection.
Core Technical Data
- Brand: Allen-Bradley / Rockwell Automation
- Catalog No.: 1771-IC
- Inputs: 8 (sink type, source load)
- Voltage Range: 10-60 VDC (operating: 42-56 VDC)
- Backplane Current: 74 mA
- Off-State Current (max): 3.7 mA
- Signal Delay (On): 17 ±7 ms (with digital filter)
- Signal Delay (Off): 20 ±15 ms
- Wiring Arm: 1771-WN (included)
- Coating: Conformal coat for PCB protection
- Dimensions: 89 x 165 x 51 mm (3.5 x 6.5 x 2.0 in)
Oiltech Controls’s Insight
This module excels in noise-prone environments. The input filter is not just a feature—it is a reliability multiplier. In our experience, plants using the 1771-IC see fewer false triggers and longer mean time between failures. For 3-wire sensors, ensure off-state leakage stays below 4 mA to avoid ghost inputs. This module is a solid choice for retrofitting older PLC-2 or PLC-3 systems with a modern, filtered input solution.
What Equipment Does It Work With?
- DC proximity switches (2-wire and 3-wire)
- Limit switches and float switches
- Pushbuttons and selector switches
- Photoelectric sensors (DC output)
- Any NPN or PNP device with sink input configuration
Installation & Wiring Notes
- Use the 1771-WN wiring arm for field connections.
- Connect field devices to the appropriate input terminals.
- Ensure the backplane provides 74 mA per module.
- Keep DC supply within 42-56 VDC for nominal operation.
- The conformal coating protects against moisture and dust.
Why Buy From Oiltech Controls?
- 15+ years in industrial automation spares.
- Global shipping with FedEx, UPS, or DHL.
- Tested surplus and refurbished options available.
- 12-month warranty on every module.
- Technical verification before shipment.
- Expert support for obsolete control systems.
Shipping & Warranty
- Same-day or 24-48 hour dispatch for in-stock items.
- Shipping carriers: FedEx, UPS, DHL (trackable).
- 12-month warranty against defects.
- Modules are tested prior to packaging.
Frequently Asked Questions (FAQ)
Q: Can I use this module with a 24 VDC sensor?
A: Yes. The 1771-IC accepts 10-60 VDC. 24 VDC sensors work perfectly. Just ensure the sensor’s off-state leakage is below 3.7 mA to avoid false ON signals.
Q: What is the difference between 1771-IC and 1771-IBD?
A: The 1771-IC is a DC sink input module. The 1771-IBD is an isolated DC input module. Use 1771-IC for standard sink-type devices and 1771-IBD when you need channel-to-channel isolation.
Q: How do I wire a 3-wire PNP sensor to this sink module?
A: Connect the sensor’s output to the input terminal. The sensor’s common goes to DC common. The module sinks current from the load. Ensure the sensor’s off-state leakage does not exceed 4 mA.
Q: My PLC shows intermittent inputs. Could this module be the cause?
A: Likely not. Check your sensor wiring and DC supply noise. The built-in filter handles most transients. For noisy environments, verify the cable shielding and grounding.
Q: Is this module compatible with PLC-5/250 processors?
A: Yes. The 1771-IC works with all PLC 5 series processors, including PLC-5/250. It uses the standard 1771 backplane interface.
Selection Guide – Which Input Module Do You Need?
- Choose 1771-IC for 8 DC sink inputs with filtering.
- Choose 1771-IB for 16 DC sink inputs (no conformal coat).
- Choose 1771-IBD for isolated DC inputs (16 points).
- Choose 1771-IL for AC/DC isolated inputs.
- Choose 1771-IQ for high-speed DC inputs.
Contact Information: For inquiries, email info@oiltechcontrols.com or call +86 158 8020 0923 (WhatsApp).
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