---
title: "Connecting to SLC"
---

# Connecting to SLC

> :::note
> This driver supports SLC 5/05 and compatible SLC processors using CSP or Ethernet/IP protocols.
> :::

## Connect to an SLC Device

This driver requires the OPC UA module to be installed and enabled. If the module is missing or disabled, the device will fault with a “Missing Dependency” error on the **Platform** **System** > **Modules** page.

1. On the Gateway, go to **Connections** > **Devices** > **Connections**.

    ![](../../devices-connections.png)

2. Click **Create Device Connection +**.

3. Select **Allen-Bradley SLC** and click **Next**.

    :::note
    SLC PLCs do not have built-in Ethernet. Use a 1761-NET-ENI, ENBT, or similar device to enable communication.
    :::

    ![](select-slc.png)

4. On the **Configure Device** screen, enter the required fields:

   * **Name**: SLC  
   * **Hostname**: IP address of the device (e.g., 10.20.4.56)

   ![](slc-settings.png)

5. Click **Create Device Connection**.

The device will be listed now on the Connections page. The status will initially show Disconnected, but will move to a Connected state.

![](slc-connected.png)

## Device Connection Settings

### Main Settings

| Name | Description |
|------|-------------|
| Name | A user-defined name for the device. This name appears in OPC item paths and the Devices list. Name must begin with an underscore or a letter, and cannot include special characters. |
| Description | Optional description to help identify the device. |
| Enabled | When selected, the device is active and available for use. |

### Connectivity Settings

| Name | Description |
|------|-------------|
| Hostname | The Hostname value is the IP Address of the SLC processor. The protocol that the SLC processor supports is automatically detected. It will use either CSP protocol on port 2222 (0x8AE) or EthernetIP protocol on port 44818 (0xAF12). |
| Local Address | The local address to connect from when establishing a TCP connection. If left blank, then the driver will select an available address. |
| Timeout | The maximum amount of time to wait, in milliseconds, for responses from the processor. |
| Connection Path | The Connection Path value is used to define the route of the PLC-5 processor to connect to. [Optional] See [Connection Path Format](#connection-path-format) for more details. |

### Advanced Settings

| Name | Description |
|------|-------------|
| Disable Processor Browse | Disables processor browse setting. |
| Zero TNS Connection | Disables the Zero TNS connection setting. |
| Browse Cache Timeout | The amount of time, in milliseconds, to cache tag structure results read from the device. |

## Connection Path Format

If the SLC is connected over DH+ through a 1756-DHRIO module, use the following format for **Connection Path**:

`1,<DHRIO slot number>,<DHRIO channel>,<DH+ node number>`

* **1**: Indicates a transition to the ControlLogix backplane  
* **DHRIO slot number**: Slot number of the 1756-DHRIO module (0–16 depending on chassis)  
* **DHRIO channel**: Use 2 for Channel A or 3 for Channel B  
* **DH+ node number**: Octal value of the SLC node, matching its configuration

### Supported SLC Connection Methods

* SLC 5/05 direct over Ethernet
* SLC 5/03, 5/04, 5/05 via 1761-NET-ENI
* SLC 5/04 via 1756-DHRIO
* SLC 5/03, 5/04, 5/05 via Spectrum Controls WebPort 500