In this video, we will connect the EXO sonde to the Modbus Signal Output Adapter, which enables integration into SCADA systems using Modbus RS-232 or Modbus RS-485 signals.
Modbus is a data communications protocol used with Programmable Logic Controllers, or PLCs, like a SCADA system, for example. SCADA systems are Supervisory Control and Data Acquisition systems often used in utilities and industrial plants.
The Modbus signal output adapter, or SOA, is intended for long-term use, and it converts the proprietary EXO sonde communication signal into Modbus RS-232 or RS-485 signals to allow for easy integration into 3rd party Modbus systems. The Modbus SOA can be used with any EXO sonde. In this video, we will be connecting it to an EXO2s.
Aside from the sonde and SOA, we will need an EXO flying lead cable, wiring terminal blocks, electrical tape, a flathead screwdriver, and the EXO sensor tool. For wiring your SOA to a PLC, refer to the PLC’s operating manual for instructions on wiring communications and power connections to the SOA. Since we will be working with electrical wiring, please follow the proper safety precautions for your equipment.
First, let’s review the adapter connections:
On the top left, we have the 2-pin 9-16 V DC power terminal. Power can be supplied directly from existing wired power from your PLC, a battery or solar panel, or a data logger. Power will go to both the SOA and the sonde. Then we have the Modbus 7-pin Input/output terminal, where you have the option of wiring to the default 485, or 232 terminals. Next, there’s the LED indicator light on the top right, which will be on with no flashing to indicate no sonde is connected or the sonde has a fault. Flashing once per second indicates the sonde is connected and functioning, and flashing once every 10 seconds indicates sleep mode. Then, the Mini USB port allows you to connect your sonde directly to a PC.
Below that is the 5-pin input terminal to connect to the EXO’s flying lead field cable. And finally, the magnetic read switch where you can use the EXO magnetic sensor tool or magnet to rediscover an attached sonde.
Next, we will wire the components. The SOA wiring will depend on which output you need and what type of power supply and system you are using. You can find a wiring example in the EXO Manual.
Let’s start by connecting the EXO Flying lead field cable to the Modbus SOA, as shown on the right side of the diagram. Make sure all the equipment is powered off.
Using a 5-pin wiring block, I will connect the black wire to the top terminal, followed by the yellow, white, grey, and then red in the last terminal. The orange wire on the flying lead cable will not be used, so it can be taped back with electrical tape. After inserting each wire into the block, use the flathead screwdriver to tighten down on the wire. Once all five wires are attached, give them a firm tug to make sure they are secure. Tape together excess wire length. Now insert the wiring block into the Modbus terminal by lining up the inputs. They should click in nicely.
On the other side of your Modbus SOA, you will need to wire the power and signal output, either RS-485 or RS-232, whichever your system requires. You can also integrate a 3rd party RS-485 to TCP/IP Ethernet signal adapter if needed. Since this setup will look different for everyone, we will not show it today. For simplicity, we have our SOA wired to a power inverter and datalogger to supply power to the system.
The Modbus SOA default settings are referenced in the EXO manual. The default output is RS-485. If you need to change any of these settings, you can use the USB port to connect to your PC. Open Kor Software, and under Instrument and Sensors, click Manage Communication Adapters. Make sure you have downloaded the latest version of Kor Software and drivers.
The Modbus SOA parameter outputs can also be configured in Kor. Alternatively, you can use your SCADA system by writing the parameter codes. The reference list of all available parameter codes for Read Holding Registers can be found in the EXO Manual.
Now we will configure the sonde deployment in Kor. Connect the flying lead cable to the EXO2. The wet-mate connector should be cleaned and lubricated with o-ring grease. Just make sure to avoid the pins. Plug in a Mini USB cable to the Modbus SOA and connect to a PC. This allows for direct communication to the EXO for configuration, calibration, and data transfer without disconnecting the field cable.
Bring up Kor software and connect the EXO. We are going to create a deployment template. Click the Deployment tab. Click Create a New Template. You can edit an existing template if you have one. Under Basic settings, set the name, logging interval, and other details. Under the adapter settings, select the parameters that will be included in the SOA output. You can also change their order.
Under the Advanced settings, you can choose to change the logging mode. Normal mode is the default logging mode, where the sonde logs one sample every logging interval; this is recommended for use when the sonde is logging data internally. We recommend Sample and Hold mode if you are connected to a PLC or SCADA system. In this mode, the last logged dataset is sent to the SCADA system; this ensures the data sent to the system matches the data stored in the sonde. And Burst mode is where the sonde is activated at the logging interval and logs multiple samples every second over a user-defined period of time. I will select Sample and Hold. You can also select parameter-based adaptive logging in this window if you wish. Click “Save and apply the template to sonde.” Now it will ask if we want to start internal logging. Since I selected Sample and Hold, I will select Yes. You can now disconnect the sonde from Kor and remove the USB cable from the SOA.
After you apply the deployment configuration to the sonde, make sure you use the EXO sensor tool over the magnet on the SOA or power cycle the SOA to rediscover the sonde and push the updated configuration.
Our system is now ready for office testing. When you deploy your system in the field, make sure it is earth-grounded for your safety and to protect the equipment. You can connect a wire from a central location of the system to either a gauge house or a grounding rod.
For deployment, the SOA should be protected from the environment. We recommend you mount it inside a sealed NEMA-4-rated waterproof enclosure with desiccant packs. You can use the panel mount or self-adhesive fastener strips that were included with your SOA to securely mount the SOA in the housing. If you need further assistance with your sonde deployments, please contact Tech Support.
Please check out our other EXO University videos, and thank you for watching.