Enable and configure the Modbus protocol

Modbus is an industrial automation protocol used for sending and receiving digital information across a single, external RS-485 serial bus.

The Modbus protocol allows Connect Tank to collect remote diagnostic information from a Modbus-enabled sensor as well as alert a user remotely if the sensor malfunctions. You can configure Connect Tank to collect remote diagnostic information from up to four Modbus-enabled sensors.

The Modbus protocol uses the serial pins on the I/O terminal block in Connect Tank. The configuration settings specified in the Modbus Protocol Settings page in Remote Manager must exactly match the Modbus protocol settings on the external sensor device(s). The configuration includes a list of variables, which specify the locations on the Modbus device that the Connect Sensor should read to collect diagnostic information.

You can also choose to enable the Modbus protocol alarm option. This ensures that when an error occurs with the Modbus-enabled sensor, error information is pushed to Remote Manager without waiting for the next scheduled push.

You can review diagnostic information from the Modbus-enabled sensor in the Data Services tab in Remote Manager. For more information about reviewing Modbus information in the data stream, see Modbus (modb1) data stream definitions.

  1. Sign in to Remote Manager.
  2. Click the arrow next to your user name and choose Open Classic Remote Manager.
  3. Click Device Management > Devices tab.
  4. Double-click the Connect Tank device you want to configure.
  5. Expand the Configuration menu.
  1. Click Modbus Protocol Settings.
  2. For the Protocol Enable (ena) field, select the On option.
  3. Determine whether error information should be pushed immediately. For the Device Status Alarm Mask (aem) option:
    • Select the On option if error information should be pushed immediately.
    • Select the Off option if error information should be pushed with the next scheduled push.
  4. The following settings must match the configuration of the external sensor device. Select the appropriate option from the list box.
    • Serial framing mode (mode)
    • Serial baud rate (baud)
    • Serial data bits (dbt)
    • Serial stop bits (sbt)
    • Serial parity (par)
  5.  For each Modbus sensor that you want to monitor, you can specify the station address and then include a list of variable addresses. The items in the list must be separated by a comma without spaces. The list is limited to 63 characters, which allows for 8 to 10 variables in a list. For more information about identifying Modbus stations and locations, see Modbus station addresses and locations.
    1. In the Station1: Client Address (saddr1) field, select the station address.
    2. In the Station 1: Variable list (vars1) field, enter the list of variable addresses.
    3. Repeat this process for any additional stations. You can specify up to four stations.
  1. Apply the configuration changes:
    1. Click Save > Schedule. The Save Device Properties dialog appears.
    2. Select Immediate.
    3. Select Schedule Offline.
    1. Click Schedule. Connect Tank downloads and applies configuration changes the next time it connects to Remote Manager.
  2. If Connect Tank is providing power to the Modbus device, you must enable the serial power output. For instructions, see Enable and configure a serial power output.

If the external sensor device has an alternate power source, you can skip this step.