--- title: Use the Status Register to Connect a PLC slug: litmusedge/how-to-guides/devicehub-guides/status-register-guide description: Learn how to use the status register option, which allows you to use a custom configuration to connect to PLC devices. docTags: createdAt: 2023-02-27T14:20:39.000Z --- The status register option in device configurations allows you to set up a connection with a PLC device that won't successfully connect using the default connection configuration between Litmus Edge and the device. # Video :::Iframe{iframeHeight="0" code=""} ::: # User Scenario The default configuration for a PLC in your production environment can't connect to Litmus Edge. You will therefore use the status register option to create a custom configuration to connect the PLC to Litmus Edge. # Set Up and Use the Status Register Option Complete the following tasks to use the status register option. ## Before You Begin For this user scenario, the Modbus slave simulator is used. To complete these steps, you will need to download the [Modbus slave simulator](https://www.modbustools.com/download.html). ## Step 1: Set up Modbus Simulator **To set up the Modbus slave simulator: ** 1. Open Modbus slave simulator. 2. Navigate to **Setup **> **Slave Definition...** 3. Configure the following parameters. **Slave ID**: 1 **Function**: 03 Holding Register (4x) **Address**: 0 **Quantity**: 10 ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/a7JBxIn3Auyh7J5gNPX33_slave-definition.png" size="50" width="402" height="339" caption="Slave Definition dialog box" position="center" showCaption="true"} 4. Click **OK**. 5. Navigate to **Connection **> **Connect...** 6. Configure the following parameters. **Connection**: Modbus TCP/IP **IP Address**: Enter the IPv4 address for your computer. If needed, use the `ipconfig` command in the command prompt window and copy the **IPv4 Address**. **Port**: 502 **IPv4**: Select this option. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/vdS2B3mGsNRoHup9jQWqF_connect.png" size="50" width="407" height="422" caption="Connection Setup dialog box" position="center" showCaption="true"} 7. Click **OK**. The simulator successfully connects. ## Step 2: Connect Modbus Device in Litmus Edge You can now follow the steps to [Connect a device](docId\:pal6ABPZbrimdU9LvGJ30). Configure the following parameters: - **Device Type**: Modbus - **Driver Name**: Modbus TCP - **Name**: Enter a name for the Modbus TCP Ethernet Driver. - **Network Address**: Enter the IP address you configured in the Modbus slave simulator. - **Network Port**: 502 - **Station ID**: This is the Slave ID configured in the Slave Definition in the Modbus slave simulator. Enter **1**. After adding the device, the device shows a successful connection to the slave simulator. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/OMi36lMOMXNQav79F8Eo8_image.png" size="50" width="420" height="344" caption="Successful connection to slave simulator" position="center" showCaption="true"} Now that the device is successfully connected, you can test the status register function. ## Step 3: Update Slave Definition Function To test the status register function, you will need to update the function parameter in the slave definition of the slave simulator. This simulates a PLC device with a default configuration that can't connect to Litmus Edge. **To update the slave definition function:** 1. In the Modbus slave simulator, navigate to **Connection **> **Disconnect**. 2. Navigate to **Setup **> **Slave Definition...** 3. Update the **Function **to **04 Input Register (3x)**. 4. Click **OK**. 5. Navigate to **Connection **> **Connect...** and click **OK**. The Litmus Edge device you created should now show a disconnected status due to the change in function from the simulator. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/35DbO-a6ptVU5ti7Fjk9P_image.png" size="50" width="419" height="343" caption="Disconnected status for device" position="center" showCaption="true"} ## Step 4: Configure Status Register in Litmus Edge You can now set up the status register option in the device configuration to successfully connect to the slave simulator. **To configure the status register in Litmus Edge:** 1. In Litmus Edge, click the **Edit **icon for the device. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/3zsxHN39b4XhTMQI10ih3_edit-icon.png" size="50" width="419" height="343" caption="Edit icon" position="center" showCaption="true"} 2. Select the **Status Register** check box. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/N37RTBhvBEwQmkawPZqyG_status-register.png" size="80" width="1182" height="751" position="center" showCaption="false"} 3. Configure the following parameters. - **Name**: I - Analog Input Registers - **Value Type**: int32 4. Click **Update Device**. The device now shows a successful connection again based on the status register configuration. ## Step 5: Test Tags Now that the device is successfully connected using status register, you can now test that tags in the device can be read. You will do the following: 1. Create a tag in Litmus Edge. 2. Update register values for the connected device in Modbus slave simulator. 3. Use [Analytics](docId:8alOe_5_c9uBqJsW0PpCX) to read the tag values and confirm the tags are successfully configured. **To test the tags for the device: ** 1. In Litmus Edge, navigate to DeviceHub > Tags. 2. Select the Modbus TCP device. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/LjWlxnCLpv9Q4FawFAR2Y_select-modbus-tcp-device.png" size="80" width="1573" height="472" caption="Select Modbus TCP device" position="center" showCaption="true"} 3. Click the **Add Tag** icon and select **Add a Tag**. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/qrtNoC3vZQrvyoRWgWvF2_add-tag.png" size="80" width="1573" height="671" caption="Add Tag icon" position="center" showCaption="true"} 4. Configure the following parameters. - **Name**: This needs to be the same register as used in the Modbus slave simulator. Select **I - Analog Input Registers**. - **Tag Name**: Enter a name for the Modbus TCP Ethernet Driver tag. - **Value Type**: int16 - **Polling Interval**: The interval in seconds that the tag will poll for data. Enter **1**. - **Address**: The register that the tag will start reading data. Enter **1**. - **Count**: The number of registers that the tag will read. Enter **5**. 5. Click **Add Tag**. 6. Click the **Copy **icon for the tag's RAW Topic. You will refer to this later. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/_8j8Ugrr8L-72n3hvwGdl_copy-tag.png" size="80" width="1573" height="457" caption="Copy icon for tag" position="center" showCaption="true"} 7. In Modbus slave simulator, double-click the cell in column 00000 and row 1. This is the cell that the tag you created will start reading from (Address parameter). Enter the value **5** and click **OK**. Do the same for row 2 to 5 and enter the following values: **11**, **22**, **44**, **66**. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/x_JvBMV25vfWrdp__ZKP2_register-tags.png" size="80" width="946" height="483" caption="Modbus slave simulator register tag values" position="center" showCaption="true"} 8. In Litmus Edge, navigate to **Analytics**. 9. Open the **Action menu** and select **Add a processor**. The *Create a Processor* dialog box opens. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/KCWg6yYzlltqQunzgVPf7_add-processor.png" size="80" width="1525" height="441" caption="Action menu for Analytics canvas" position="center" showCaption="true"} 10. Select **DataHub Subscribe**. 11. In the **Topic **field, paste the tag's RAW topic that you copied earlier from step 6. 12. Click **Save**. 13. Click the **View **icon for the processor. ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/yPS_DeHjLM_5p7q51_YY7_view-icon.png" size="80" width="1573" height="497" caption="The View icon" position="center" showCaption="true"} 14. Under *Instance Messages*, verify that *success *displays **true **and *value *displays the five values you configured in the Modbus slave simulator (**5**,**11**,**22**,**44**,**66**). ::Image[]{src="https://api.archbee.com/api/optimize/SSUUxKZUk9bFTEPNn_6Zo/Bu0ggVRG-onTZhDAIUbij_tag-messages.png" size="80" width="1573" height="731" caption="Instance messages for tag" position="center" showCaption="true"}