Today you'll find Ethernet in almost every manufacturing facility, and on most all modern automation systems. But many facilities also have an installed base of legacy PLC-5 systems, and often clients call asking how they can add Ethernet connectivity to their legacy PLC-5's.
Before we answer that question, lets first review the communication options available on the PLC-5 processor.
The original processors (5/10, 5/12, 5/15, & 5/25) which were released beginning in 1985, came with two connectivity options built into every model:
- Data Highway Plus (DH+, also known as Peer Communication Interface or PCI)
- Remote I/O (RIO.)
The second generation of PLC-5 processors (5/11, 5/20, 5/30, 5/40, 5/60, 5/80,) known as the “New Platform” (NP) PLC-5, had an additional 25 pin RS-232 port, and could also be ordered with an optional Ethernet or ControlNet port.
So for all those PLC-5 processors without the built-in Ethernet port I list five options below which allow you to add Ethernet communications to your non-Ethernet PLC-5:
New Option: ANC-100e EtherNet/IP to DH+ Gateway
From ANC: “The ANC-100e is an economical and high performance, “pocket-sized” converter interfacing Factory Automation Devices between Ethernet/IP and Allen-Bradley Data Highway Plus DH+”
Pros:
Works with any DH+ device
Cons:
It's not free?
PNs and Prices
ANC-100e EtherNet/IP to Allen Bradley DH+ Gateway $1,195.
Option 1: EtherNet/IP to Allen Bradley Remote I/O or DH+ Gateway (works with all DH+ devices)
From Prosoft: “The EtherNet/IP to Remote I/O or DH+ (AN-X2-AB-DHRIO) Gateway is designed to help customers initiate a phased migration approach to replacing or upgrading legacy Remote I/O, HMI's or Drives. The AN-X2-AB-DHRIO gateway has multiple operating modes that are selected during initial configuration and are described below..”
Pros:
Works with any DH+ device
Cons:
It's not free?
PNs and Prices
AN-X2-AB-DHRIO EtherNet/IP to Allen Bradley Remote I/O or DH+ Gateway $1,895.
Option 2: 1756 DH+ to Ethernet Gateway (works with all DH+ devices)
A very common option to bridge from Ethernet to DH+, CNET, and DNET, a 1756 chassis with an Ethernet module and a single DHRIO module provides for the bridging from Ethernet to two DH+ networks at 57.6K or 115K, or one DH+ at 230K.
Pros:
One Ethernet gateway to many networks
Direct access to PLC-5 Data Tables
No programming needed to bridge Ethernet to DH+
Add additional modules for additional networks: ControlNet, Devicenet, DH+, DH-485, or 3rd party modules from Prosoft
Cons:
Expensive solution for a single PLC
PNs and Prices
1756-A7: 7 SLOT CONTROLLOGIX CHASSIS $504.00 list price from A-B
1756-ENBT: CLX ETHERNET/IP BRIDGE $2150.00 list price from A-B
1756-PA75: 85-265V AC POWER SUPPLY $911.00 list price from A-B
1756-DHRIO: DH+/RIO BRIDGE $1,910.00 list price from A-B
(Obsolete) Option 3: DF1 to Ethernet/IP converter: (New Platform PLC-5 models only)
If your New Platform PLC-5’s serial port is available, you can easily add a DF1 to Ethernet/IP converter (1761-NET-ENI.)
Pro's:
Least expensive option
Direct access to PLC-5 Data Table
Has built in email capability (converts PLC MSG to an email)
ENI configuration is done with a free utility
Con's:
Only three simultaneous bi-directional connections to PLC-5 at any given time
The PLC-5 serial port is limited to 19.2K (low bandwidth)
Requires PLC-5 NP processor with available serial port
If you have an HMI on the serial port you can use the A-B Serial DF1 port splitter (1747-DPS1) but you'll be splitting the bandwidth with the HMI.
PNs and Prices
1761-NET-ENI
$893.00 list price from A-B
1761-CBL-PM02
$74.10 list price from A-B
$25.00 from Amazon
9 Pin to 25 Pin adapter
$10 from Amazon
(Obsolete) Option 4: ENET Sidecar: (New Platform PLC-5 models only, firmware upgrade may be needed, )
If your New Platform PLC-5 has the correct firmware, or if you're willing to purchase the firmware upgrade, and you have the ability to move whatever module you have in the first I/O slot (directly to the right of the processor,) the 1785-ENET Ethernet sidecar is an option you can consider.
Pros:
High Speed connection to PLC-5
Direct access to PLC-5 Data Table
Channel 3a configuration is simple
Cons:
Need to move and readdress I/O module in slot 1
Will likely need to update PLC-5 firmware chip which can be expensive
PNs and Prices
1785-ENET
$3720.00 list price from A-B
5/80 Firmware
~$685.00 from A-B (most expensive version, price circa 2005)
(Obsolete) Option 5: Prosoft Ethernet Module for 1771 Chassis and all PLC-5 Processors: (works will all PLC-5 models)
From Prosoft: “Support for the storage and transfer of up to 4000 registers to/from the PLC processor using the block transfer. The module can send read or write commands to remote devices on the Ethernet/IP network. The MVI71-DFNT also has 20 servers that allows the module to receive commands from remote devices. The MVI71-DFNT Pass-Through server allows the user to edit, download, and upload the PLC ladder logic using an Ethernet connection. Up to 100 commands can be configured by the user.”
Pros:
Works with any PLC-5 in any SLOT
Cons:
Requires programming (Prosoft tech support historically has been good)
– Block Transfers needed in PLC-5 Program
PNs and Prices
MVI71-DFNT EhterNet /IP Communication Module ~$2,159 (circa 2005)
I hope you’ve found this article about how to add Ethernet to non-Ethernet versions of the Allen-Bradley PLC-5 helpful. If you have a question or would like to offer your own option please click on the “post a comment or question” link below to comment on this article.
Until next time, Peace ✌️
Shawn M Tierney
Technology Enthusiast & Content Creator
Have a question? Join my community of automation professionals and take part in the discussion! You'll also find my PLC, HMI, and SCADA courses at TheAutomationSchool.com.
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Thank you Shawn for your post that helped me to see the different solutions to connect old PLC5 to Ethernet. .
Regarding the connection from PLC5 to 1761-NET-ENI, the proposed 1761-CBL-PM02 cable will not fit because the cable has a 9 Pin SubD connector and the PLC5 has a 25 Pin SubD connector. An adapter is required I think.
Alan
Good evening Alan,
Thanks for your comment. Yes, you are correct about the PM02 which is why I also listed the 9-25 pin converter under it – sorry it wasn’t more obvious.
Have a great evening,
Shawn Tierney
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