# Allen Bradley SLC-500 PLC and Node Red

**URL:** <https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725>\
**Category:** General\
**Created:** [19 January 2025 10:12 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725 "2025-01-19T10:12:12Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![Surefire01](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/surefire01/32/71490_2.png) [@Surefire01](https://discourse.nodered.org/u/Surefire01)\
**Post date:** [19 January 2025 10:12 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/1 "2025-01-19T10:12:12Z")

</div>

Hi Folks.  
In a previous life I used Allen Bradley SLC-500's to teach electrical apprentices the basics of PLC's. These were programmed using RSLinx and RSLogix installed on a laptop and communicating through an RS232 cable. I now run Node Red on a Raspberry Pi and was wondering if there is anyway to integrate Node Red into the SLC500 in some way. I know these PLC's are obsolete but I have one at home and would love to tinker with it. By the way I still have a laptop running Windows XP which has a licenced copy of RSLinx and RSLogix installed.  
Thoughts?

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [19 January 2025 11:08 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/2 "2025-01-19T11:08:24Z")

</div>

What protocols does the plc have available? EtherNet/IP? DF1? Modbus RTU?

---

<div class="post-metadata">

**Author:** ![Surefire01](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/surefire01/32/71490_2.png) [@Surefire01](https://discourse.nodered.org/u/Surefire01)\
**Post date:** [19 January 2025 12:44 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/3 "2025-01-19T12:44:47Z")

</div>

The SLC 5/03 CPU has sockets for RS232 which is used for programming with the laptop and there is a socket that looks like an ethernet port (but I dont think its a regular ethernet configuration) called DH485

 ![SLC500](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/4/043517cd45f72c3b569e51c6954b92fe69754f9a.jpeg)

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [19 January 2025 13:30 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/4 "2025-01-19T13:30:43Z")

</div>

You are right. The RJ45 is not Ethernet. It runs a serial network called "Data Highway 485" (DH485) which, if i recall, is a proprietary AB protocol. The RS232 port however can be setup to communicate on a protocol known as DF1 which is easy to connect with an ordinary serial port. The DH485 port requires a converter e.g. 1747-UIC (a USB to DH485).

You could try one of the 2 DF1 offerings in the node catalog:  
[https://flows.nodered.org/search?term=DF1&type=node](https://flows.nodered.org/search?term=DF1&type=node)

---

<div class="post-metadata">

**Author:** ![Surefire01](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/surefire01/32/71490_2.png) [@Surefire01](https://discourse.nodered.org/u/Surefire01)\
**Post date:** [19 January 2025 13:57 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/5 "2025-01-19T13:57:26Z")

</div>

Yes Steve I seem to recall one of my colleagues using a 1747-UIC adapter with some success, I'll look into it.

---

<div class="post-metadata">

**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [19 January 2025 14:08 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/6 "2025-01-19T14:08:39Z")

</div>

If you use the serial port (RS232) you can make (probably buy) a cable much cheaper & the DF1 protocol is quite simple to implement (and there are existing pre-build nodes already implementing the DF1 protocol as linked above).

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/0/603ab44691a8b1caa68e3b0885dc3df13d46b119.png)

I dont _think_ there are any nodes available to "speak" to Data Highway and I am not certain the protocol can be changed to DF1 on the DH485 port.

---

<div class="post-metadata">

**Author:** ![jblack](https://avatars.discourse-cdn.com/v4/letter/j/c4cdca/32.png) [@jblack](https://discourse.nodered.org/u/jblack)\
**Post date:** [20 January 2025 15:02 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/7 "2025-01-20T15:02:07Z")

</div>

Testing my old knowledge here …  
If you have a 5/03, 5/04 processor I think they support Modbus RTU out the serial port. Might investigate that avenue…  
Cheers!

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [20 April 2025 15:02 UTC](https://discourse.nodered.org/t/allen-bradley-slc-500-plc-and-node-red/94725/8 "2025-04-20T15:02:45Z")

</div>

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.