1785-L20E

Technical specifications

Manufacturer

Allen-Bradley

Manufacturer part no.

1785-L20E

Type

PLC-5 Ethernet processor

Application

PLC controller

Used with

1771 I/O chassis (leftmost slot)

Processor

PLC-5/20E

Maximum user memory (words)

16 k

Total I/O, maximum

512 any mix or 512 in + 512 out (complement)

Channels

1 Ethernet; 1 DH+; 1 DH+/remote I/O

I/O chassis, maximum total

13

Remote I/O chassis, maximum

12

Power dissipation, maximum

19 W

Backplane current load

3.6 A

Operating temperature

0...60 °C (32...140 °F)

Storage temperature

-40...85 °C (-40...185 °F)

Relative humidity

5...95% noncondensing

Vibration

2 g @ 10...500 Hz

Shock

Operating 30 g; non-operating 50 g

Enclosure type rating

None (open style)

Time-of-day clock/calendar

Maximum variation at 60 °C: ±5 min per month; typical at 20 °C: ±20 s per month

I/O modules

Bulletin 1771 I/O, 1794 I/O, 1746 I/O, and 1791 I/O, including 8-, 16-, 32-pt and intelligent modules

Hardware addressing

2-slot, 1-slot or 1/2-slot

Location

1771-A1B, -A2B, -A3B, -A3B1, -A4B chassis; leftmost slot

Replacement battery

Allen-Bradley 1770-XYC

Available cartridges

1785-RC Relay Cartridge

Memory modules

1785-ME16, 1785-ME32, 1785-ME64, 1785-M100

Isolation

50V basic insulation between communication ports and between communication ports and backplane; tested to withstand 500V rms for 60 s

Wire size

Ethernet: 802.3 compliant shielded or unshielded twisted pair; remote I/O: 1770-CD cable

Weight

3 lb, 1 oz (1.39 kg)

Technical documents (1)

• Rockwell Automation publication 1785-IN063 (specifications)

Key features

• Ethernet channel for 802.3 compliant twisted pair cabling
• Works with Bulletin 1771, 1794, 1746 and 1791 I/O
• Supports up to 12 remote I/O chassis
• Memory modules 1785-ME16, -ME32, -ME64 and 1785-M100 available
• Open style unit rated for 0 to 60 °C operation

About the Allen-Bradley 1785-L20E

The Allen-Bradley 1785-L20E is a PLC-5 Ethernet Processor, listed by Rockwell Automation as the PLC-5/20E. Rockwell publication 1785-IN063 gives a maximum user memory of 16 k words and a maximum of 512 I/O, either any mix or 512 in and 512 out (complement). It has one Ethernet channel, one DH+ channel and one DH+/remote I/O channel, and weighs 3 lb 1 oz (1.39 kg). Rockwell's lifecycle record shows it as discontinued on 31 December 2014.

What is the 1785-L20E used for?

The 1785-L20E runs the control program in a PLC-5 system and communicates over its Ethernet, DH+ and DH+/remote I/O channels. It sits in the leftmost slot of a 1771-A1B, -A2B, -A3B, -A3B1 or -A4B chassis and scans Bulletin 1771, 1794, 1746 and 1791 I/O using 2-slot, 1-slot or 1/2-slot addressing. Rockwell gives a maximum of 13 I/O chassis in total, of which up to 12 can be remote I/O chassis.

Lifecycle and successor

Discontinued.

Before you order

What to photograph or confirm so the right unit is quoted.

Check that the label reads catalog number 1785-L20E, and note the series letter and firmware revision printed on it. Send us a photo of the label if you want these details checked against your installed processor.