PLC-5 Platform (Legacy) — Available Products
Allen-Bradley 1785-L11B
$1,221.00
Allen-Bradley 1785-L20B
$1,404.00
Allen-Bradley 1785-L20C15/E
$3,159.99
Allen-Bradley 1785-L20E
$4,339.99
Allen-Bradley 1785-L30B
$3,230.00
Allen-Bradley 1785-L40B
$1,908.99
Allen-Bradley 1785-L40C15/F
$4,484.00
Allen-Bradley 1785-L40E
$2,783.00
Allen-Bradley 1785-L40L
$3,628.00
Allen-Bradley 1785-L60B/E
$2,947.00
Allen-Bradley 1785-L80B
$2,622.00
Allen-Bradley 1785-L80E
$3,699.99
Allen-Bradley 1785-LT3
$5,202.00
Allen-Bradley 1785-M100/A
$1,597.00
Allen-Bradley 1785-TR10BT
$853.00
Allen-Bradley 1785ENET
$1,394.99
Overview
PLC-5 is the iconic Allen-Bradley large-frame controller used throughout the 1990s and 2000s in heavy industry. While end-of-life, PLC-5 systems still control critical processes in refineries, mills and utilities. Palm Parts Solution supports these installations with refurbished 1785 CPUs and 1771 I/O.
Machine down? Get a fast quote on PLC-5 Platform (Legacy) parts.
New, surplus, and refurbished Allen-Bradley options. Request a quote or speak directly with an automation specialist for emergency sourcing.
Common Applications
- Sustaining critical legacy PLC-5 installations
- Spare parts programs for refineries, mills, utilities
- Bridge phase of ControlLogix/CompactLogix migrations
Common Faults
- Major fault S:11 — many causes; cross-reference Rockwell pub 1785-6.1
- Backplane I/O remote rack drop — ControlNet keeper or terminator issue
- Channel 1A/1B (DH+) noise — degraded twinaxial cable
- EEPROM corruption — old chassis, recommend full migration
- Power supply 1771-Pxx fault — replacement stock now surplus-only
Troubleshooting Basics
- Use 6200 software or RSLogix 5 to read S:11 and S:12 major/minor faults.
- Reference pub 1785-6.1 for fault-code definitions.
- Inspect 1771 chassis for bent backplane pins.
- For ControlNet, run RSNetWorx and verify keeper.
- If hardware is intermittent, plan a ControlLogix migration — repair stock is exhausted.
Replacement Options
Palm Parts Solution sources every PLC-5 Platform (Legacy) part in three conditions:
- New — sealed, factory-fresh stock
- Surplus — never installed, original packaging, full warranty
- Refurbished — bench-tested to OEM spec, 12-month warranty
Most orders ship same day from US warehouse stock. Critical machine-down requests can be expedited worldwide.
Migration Recommendations
Discontinued. See our PLC-5 Migration Guide. Recommended target: ControlLogix 1756-L8x.
Compatibility
- 1771 I/O modules in 1771-Axx chassis
- DH+, ControlNet, RIO networks
- RSLogix 5 software
Advantages
- Drop-in replacements with 30-day warranty
- DH+ and Remote I/O bridge compatibility
- Migration consultation available
Series in this family
1771 I/O modules for PLC-5 — digital, analog and specialty.
1785 PLC-5 processors — Standard, Enhanced, Ethernet, ControlNet.
Frequently Ordered Together
- 1771-Pxx power supply
- 1771 discrete I/O
- 1785-KE serial bridge
- ControlNet 1786 media
Compatible & related families
Why Buy From Palm Parts Solution
DHL, FedEx, UPS — door-to-door in 1-4 business days.
RFQs sent during business hours are answered the same business day.
New, surplus and refurbished Allen-Bradley options — request current availability.
24/7 emergency sourcing for production-critical failures.
Custom pricing on volume, repair, and hard-to-find SKUs.
Talk to engineers, not call-center agents.
We hunt down discontinued and obsolete parts globally.
Lifecycle-end Allen-Bradley parts — sourced, tested, warrantied.
Buying guides & technical resources
Replace 1785 PLC-5 processors and 1771 I/O with ControlLogix 1756 — conversion tools, chassis adapters, and timing.
A practical buying guide for Allen-Bradley PLC-5 Platform (Legacy) — models, prefixes, compatibility and replacement options.
Frequently asked questions
Is PLC-5 end-of-life?
Yes — EOL in 2017. Palm Parts Solution stocks refurbished 1785 processors and 1771 I/O for installed-base maintenance.
Which software programs PLC-5?
RSLogix 5. Programs can be migrated to Studio 5000 for ControlLogix.
How do I migrate from PLC-5 to ControlLogix?
Use the Logix migration tool plus 1492 wiring-system conversion modules and 1756 DH+/Remote I/O bridges to keep field wiring and remote racks.