HART Configuration in Schneider PLC

2 August, 2020.

In this post, we will understand how to configure a HART device in a Schneider (M580) PLC. (Click on the images for a more zoomed view)

Hello programmers. Welcome back to our study. I hope you enjoyed reading the first part on understanding the HART protocol in general.

Let’s get a look now on how to configure a HART device in a Schneider PLC (M580).

First of all, the most crucial requirement is a proper DTM/DD file as discussed in the first part. Be it any PLC, an improper DTM/DD file of the HART device cannot help you make a connection with it. To find that proper file, you need to be well versed with the terms – HART universal revision and device revision. In simpler terms, you can co-relate it with a firmware version of the PLC. If you read the technical documentation of that device, you will find it’s default HART universal revision and it’s own revision number (device revision). They have options to select the revision according to your needs. You can set them via a HART communicator tool or manually by entering the parameters in the device menu shown on it’s display.       

Let me explain you with the device that I have used here for study. I have used Rosemount 3051-T pressure transmitter (Emerson-make), which is HART-enabled. Refer the below image. The default settings in this device are – HART revision 5 and device revision 9. If you visit the website of Emerson for downloading the DTM file, then you will find various versions of all the devices. Selecting the right one requires sound knowledge of the specifications of device. When you download a given link, most of them have a readme file in it; which shows the supported devices in the DTM file and other information related to HART communication. You can use it for confirmation. Many a times, you cannot find a DTM file for a specific device; you can then use a general DTM file of that manufacturer or confirm with them about the DTM file for any issues.

After you have installed the software (DTM file setup), you have to update this DTM file in the PLC software. Without updating the DTM catalog, you cannot see this file in the software. For the PLC which we are referring here, use Unity Pro V13.1 or above. The software versions mentioned are stable and proper for HART communication. Now, refer the below video.

 How to Add HART DTM in Unity Pro

I will explain it in the following steps:

·     In the Tools option, go to Hardware Catalog.

·   Then, go to DTM catalog inside it.  You can see four sub-topics under it – Device Types, vendors, groups and protocols. In the protocols section, go to HART. I had already updated the DTM file earlier; that’s the reason the device name is showing here (3051 HART 5). For first timers, you will find that the device type you want is not installed. So, click the Update button below. After updating, you will find the device name. This indicates that the device DTM file has been installed successfully in the PLC software.

After the DTM has been successfully installed, you can now assign to it any PLC channel  for use. Refer the below video.

How to Add a HART Device in Unity Pro

I will explain it following steps:

·    We will use BMEP582040 CPU for study. The security features are initially disabled in the CPU. You will need to unlock it.

·    Now, set the IP address of the CPU. When you validate it, it will ask for a service to be enabled (TFTP). So, unlock / enable all the security options and tick all of them as shown.

·  Then, add the BMEAHI0812 module in the slot required. Only 4-20 mA option is available in this module as per HART protocol. You can scale the raw counts as required by you.

·    Now, go to DTM Browser in Tools option. Right click the BMEP58_ECPU_EXT option and click Add. You have to add the analog module here. Select the module as shown and add it.

·    Double click the BMEP58_ECPU_EXT option. It will open the communication settings for this CPU. Here, first set the Channel properties; the IP address of your desktop. If not set properly, then you won’t be able to go online in the HART device. Then, click BME_AHI_0812. In the address setting tab, you have to set the IP address of the module and it’s position in the CPU system. M is the notation for it’s local CPU position and C is the notation for it’s remote CPU position. Here, we used Mx80_02; as our module is located in the 2^nd slot of the local rack.

·   Now, double click the BME_AHI_0812 option in the distributed bus as shown. It shows the overall HART settings of the module. In the process data tab, you can define which variables you want to read from the device. By default, four variables are read from a device – PV, SV, TV and QV. In the parameter configuration tab, you can define which channels are to enabled / disabled for HART communication. In the security tab, you have to disable the access control option. This practice is normally done because sometimes, some screens in the HART device don’t show proper records; when you go online in it. Disabling this feature allows you to fully access all the windows inside the HART device.

·    Right click the BME_AHI_0812 option and add the HART device (DTM) in the channel you want.  

After the PLC has been assigned with HART settings, you can now view it online. Refer the below video.

How to View HART device online in Unity Pro 

I will explain it in following steps:

·    Right-click the module where the device has been connected and click Connect. The module will be highlighted in bold as shown in video.

·   Again right-click the module and go to Device Menu -> Additional Functions -> Transfer to FDR Server. FDR stands for Fast Device Replacement. This service stores network and operation parameters of devices on the network. If a device is replaced, the service automatically configures the replacement device with parameters similar to those of the removed device. It is essential to transfer the latest parameters to FDR server in the PLC; otherwise the bus state LED in the analog module will blink and HART communication won’t happen properly.   

·    Right-click the channel where the device is connected and click Connect. The   device will show as highlighted in bold; if the connection is proper.

·   Double-click the device and you can see the overall parameters of the device as shown in video. You can even configure the device from this window.

In short, you can overall control the actual device from just sitting in the centralized PLC room and even configure it, if required, without going in the field. This reduces your overall installation time and provides a greater control in the system. Each and every parameter of the device can be viewed here through HART communication.

This lesson has been a basic introduction to the general theory of HART communication. The ways the PLC analog I/O modules (HART-based) are built differ between manufacturers and PLC models, so I have just covered general principles without enough detail to implement them in any given PLC system. I have also not attempted to cover every type of device. Each manufacturer has unique ways of handling measurements, and there are many other sorts of instruments that we have not included here.

 

Thank you guys; I hope you enjoyed reading the practices normally used for this type of study in industrial automation. If you have any views or know some more methods, then I would be happy to get a comment from you.