[00:00] In this lesson, I'll demonstrate how to connect to a SLC using Data Highway Plus from a ControlLogix Gateway. Before walking through the steps, I'd like to take a look at an example diagram. This diagram depicts three SLC devices connected to a ControlLogix gateway via Data Highway Plus, or DH+, for short. To connect to these PLCs from Ignition, we need to navigate into the first PLC via its ENBT module, out one of its DH+ channels and into one of the SLCs. We can tell Ignition how to navigate this route with a connection path, which is a comma separated list of numbers that tell how to get to the target PLC. Connection paths will vary depending on your setup, So let's take a look at a table with the rules on creating one. The first number is always going to be a one, and that tells Ignition to move to the back plane of the first PLC. The second number is the slot number of the module to move to. We would want to move to the DHRIO module in slot number three. So the second number in the connection path would be a three.

[01:03] The third number is the exit port or channel of that module that'll be exited through. In this diagram, that depends on the desired PLC. If connecting to SLC X, then we'd want to use DH+ Channel A, which uses the number two. If connecting to SLC Y or Z, then we'd use the DH+ channel B, which is three. The fourth number is going to depend on the module we're connecting to in the target PLC. This will either be an IP address of an EMBT module, a ControlNet address, or a DH+ station number. In this example, we're connecting via DH+, and the station number will vary depending on the PLC. We would put 21 for SLC X, 40 for SLC Y, or 41 for SLC Z. A really important note about the DH+ station numbers is that these are octals. So be sure to put your station number in octal format and not in decimal format. If we were connecting to another ControlLogix device, we'd want to include another one and zero to move to the back plane and then the processor, but that's not required with PLC5s or SLCs.

[02:04] Now that we've walked through how to build a connection path, let's see how this is actually done in Ignition. I'll start in the config section on my gateway webpage, and I'll scroll down to OPC UA and click on device connections and create a new connection. In this case, I'm going to connect to a SLC, so I'll choose the Allen-Bradley SLC driver. I'll need to give the connection a name, so I'll just call mine SLC DH+. Next, I need to specify the host name or IP address of the ControlLogix gateway. So if we look back at that example diagram, this will be the first PLC. Then I need to enter my connection path. The path is gonna look a little different than the examples we looked at earlier, but it's built in the exact same way. My first number is going to be a one to move to the back plane of my gateway. Then my DHRIO module is in slot number six. I wanna move out of DH+ channel A, so I'll need to put a two. Then the fourth number is the DH+ station number, which in my case is one.

[03:04] Now that I have my specific connection path configured, I can create the connection. Once my device status says connected, I can confirm I'm getting values by navigating through the OPC quick client, I'll find my device, and I can start seeing my tags.