Modbus RTU is a famous layer 2 fieldbus protocol used in wide range of applications since the mid 80’s and it has its encapsulation in a Ethernet frame, on TCP/IP protocol of layer 4 – 3 of OSI model. It can be used on Ethernet networks though a logic IP address, Modbus TCP uses the same function codes of RTU. The main advantage is that it is faster and can be used to send or receive data through any Ethernet device such as switches and routers in different topologies like star, tree or other line topologies using TCP/UDP/IP protocols in Layer 3-4. It can be installed in Standard 10, 100 or 1000 Mbit/s Ethernet technology based on copper cables, fiber optics or wireless standards can be used. Number of stations is almost infinite and it can go up to a speed of 1.5 Kbyte per telegram frame.
MODBUS RTU is a layer 2 network protocol created in the end of the 70’s with the necessity of a fieldbus protocol in industry to transmit and receive data in a simple way through the many devices of a network, in mind. MODBUS RTU uses RS-485 electrical standards and works on a Master-Slave setup, where a master writes and reads data into the registers of the slaves in the network. It has become the default protocol in many industry devices like PLCs, drives, sensors and it is highly used nowadays.
The Delta C2000 also uses MODBUS RTU as a built-in communication protocol. In this application note we are going to learn how to set up a Master – slave configuration, write, read and program the internal PLC with ISPsoft to work on a peer-to-peer (P2P) application with 2 motors, one used as a master and other as a slave. P2P is used when we want both motors to run at the same speed together in an application and monitor their current, its typical use can be applied to pumps, fans, conveyors, rollers. It can be also taken as an alternative for the analog input/output of the drive, when we need more than just 2 measurements. Delta C2000 also permits to create a small Text panel customized display with TPEditor, which we will follow at the end of the chapters.
This week we would like to show you two new function blocks (FB) that we have developed to make even easier to use Delta Industrial Automation products.
Usually we need to control several AC drives from a single Master PLC and Modbus communication is a cheap and helpful way to get it.
In order to reduce programming and commissioning time we have developed two FB:
COM2_VFDLINK: Configures the communication parameters (baudrate, number of bits, parity,…) that all the nodes on the network have to share and informs about the communication state of each node.
DELTA_VFD: Controls each one of the slaves VFD, we can Start/Stop, Forward/Reverse, frequency command and reset faults. On the other side, the FB informs us about the status of the drive, alarm code, output frequency and output current.
Below you’ll find the FB library ready to be imported in your ISPSoft and a little pdf explaining the I/O of each FB, enjoy it!
DVP12-SE PLC can be configured to exchange data between other PLCs via Ethernet(modbus TCP/IP) by using DCISoft Software. DCISoft Software is an integrated configuration tool of Delta network modules for WINDOWS operation system. Below is how to configure DVP12-SE for Data Exchange with other PLCs.
Ethernet function of DVP12-SE PLC
Follow the steps below to configure DVP12-SE for Data Exchange.
1. Communication Setting: Start DCISoft in your PC, and click Communication Setting on the Tools menu.
When the DCISoft opens as shown above,Click the communication settings icon on the tool menu as shown below. Set the communication type and the communication parameter that you prefer to use on your PC for connecting the DCISoft with the DVP12-SE PLC .
2. Auto Search
After setting the communication type and communication parameter, then push the “Auto Search” button to search for the DVP12-SE in the DCISoft for configuration.
3. Setup Overview : after the step above, the interface below will appear. Double-click on the DVP12-SE module icon contained in the interface below to enter the setup overview page.
4. Overview
After the step above, the interface below will appear which contains several tabs in the tool bar. The first tab is the overview tab, this tab shows the current basic status of the DVP12-SE PLC module. I will further talk about theBasicand theData Exchangetabs used for the configuration of the DVP12-SE PLC.
5. Basic settings
Push the basic tab, the interface below for setting the network parameter will appear.
5.1 Module name: There can be many DVP12-SE on the network. Thus, you can set up a module name for each module to identify the module when you need to use them.
5.2 Network setup: In the IP configuration field, you can Enable DHCP (DHCP: is Automatically updated by the server. There has to be a server in the LAN) or static IP. (Static IP: Is Preset or manually modified by the user). if you choose Static IP, manually modified the; IP address, Subnet mask(Netmask ) and the Gateway IP.
6. Data Exchange
Click the data exchange tab, the interface below will appear. The Data Exchange is used for configuring exchange of data between PLC via network. A Delta Ethernet master can read/write data from/into a slave.
If a device which is not a Delta PLC is connected, users can use the hexadecimal four-digit MODBUS address of the device for data exchange.
6.1. Enable data Exchange:
Users can enable or disable a data exchange. After a data exchange is enabled, the data will
be exchanged
6.2 .Enable Condition:
In theenable condition field,you can select Always Enable,Program Control or PLC Run. If Always Enable is selected,DVP12-SE will execute data exchange continuously until the setting in DCISoft is changed.
If Program Control is selected, DVP12-SE will execute data exchange according to the
program setting. If PLC Run is selected, DVP12-SE will execute data exchange when the DVP12-SE Run Mode switch is activated
6.3. Slave ID, IP Address and Enable (Station Address-IP Address:)
You have to type in the IP address of the slaves. for example, If the IP address of a slave is 192.168.0.1, and the station number of the slave is 1, you can type 1 in the first Slave ID cell, select the box in the first Enable cell, and type in the first IP Address cell. You have to enable and include the IP addresses of the other PLC that will be slaves
6.4. Master Device, Slave Device, and Quantity:
below is a brief information about the function of Master Device, Slave Device, and Quantity in data exchange dialog box of DCISoft.
In the Master Device, Slave Device cell, if the the slaves device is a Delta PLC, enter the starting D register that you will use for data exchange.
If the slave is a third party device(not a delta PLC), enter the an hexadecimal four-digit MODBUS address that the device will use for data exchange. see below the meaning of the arrow signs in the master device and slave device column of data exchange page in DCISoft.
Reading (←): Initial reception register in a master← Initial transmission register in a slave
Writing (→): Initial transmission register in a master→ Initial reception register in a slave
6.5. Quantity: A slave station can send 100 pieces of data at most and receive 100 pieces of data at most Simultaneously
See explanation below on how the Quantity field of data exchange works.
From the figure above, with the quantity specified as 100, see explanation below what the specified D registers does.
writing data from the slave side and receiving data at the master side (← )
Looking at the first row of the Master Device and Slave Devicecolumn as contained in the figure above, The master will use D register ; D0, D1……….up to D99 (that is possible 100 pieces of different data base on the “100” Quantity Specified in DCISoft) to receive the data written by D99, D100…..up to D199 of the slave simultaneously. (that is possible 100 pieces of different data base on the “100 ” Quantity Specified in DCISoft)
writing data from the master side and receiving data at the slave side (→)
Looking at the second row of the Master Device and Slave Devicecolumn as contained in the figure above, The master can write data to the slave D register using D200, D201……up to D300 and the slave can read this data using D300, D301…D400.
From the configuration above, I can send and receive up to 100 pieces of different data by enabling data exchange and specifying a quantity of 100.
7. Reconstruction
To save your configuration to your PC desktop or USB stick, push the new button as show above and save the DCISoft file
Example
Look at the video below to see how I send and receive data between two DVP12-SE using the configuration that I explained earlier above, I use one DVP12-SE PLC as a master and the other DVP12-SE PLC as a slave for data exchange.
Indicated for beginners, experts, professionals and amateurs.
Our brand new Delta starter kit is ready for you.
The idea is give you quick and easy system configuration to practice your programming skills.
There’s 2 starter kits, the Standard and the Ethernet, feel free to choose whatever you prefer just clicking on below link. Starter kit landing page
You just need to add your personal data on that webpage and our partners will contact you for the delivery.
The Kit is composed by PLC, HMI, power supply and all the necessary cables for program them. It also came with USB disk with several training examples and manual.
You can find a description of both kits on this link
In case you need more exhaustive information use this other one link.
This is the perfect kit for everyone who wants to introduce in Delta programming software.
In case you already have your Delta elements, and just want the training tools, feel free to download all the information for free from our website.
Enjoy, and do not hesitate to share your experience with us.
Probably some of you already know the PLC Link feature of our DVP series PLCs, it allows us to easily exchange data between the master PLC and several slaves saving a lot of programming time.
Slaves can be PLC, drives, temperature controller and, in general, any equipment that includes and RS485 Modbus port.
For those who don’t know this feature here you can find other posts in this blog with detailed information:
Exchange between Master PLC and Slave drive (VFD):
Read up to 50 words (16 bits variable) from each slave.
Write up to 50 words (16 bits variable) to each slave.
Today I would like to show you how our PLC DVP12SE (Link) is able to overcome this limitations and increase the number of slaves and the number of data to be exchanged.
Using the DVP12SE PLC (fw versions 1.6 and above) you will be able to:
Communicate with up to 32 slaves.
Read up to 100 words (16 bits variable) from each slave.
Write up to 100 words (16 bits variable) to each slave.
Let’s take as an example an application where we want to communicate with first slave (ID1) and a second one over the 16 standard slaves, the 20th (ID20) for instance, at the end of this post you’ll find the example programs to be downloaded on the Master and in the two slaves.
First of all, we have to be sure that the communication parameters are the same on all the nodes connected to the Modbus (ASCII/RTU, baudrate, data bits, parity,stop bits) and also that all have a different node number.
Two internal bits are very important in order to start the PLC Link functionality, M1350 and M1351:
Also we have to indicate to our PLC that we want to access to more than 16 slaves and that we want to read/write more than 50 words on each slave:
Next step is to assign to each slave (ID1 to ID32) his configured node number into the Modbus (in this case we have configured ID1 with node 1 and ID20 with node 20):
In order to configure the PLC Link there’s no need to program complex polling structures nor keeping into account communication timeouts or errors in order to resend Modbus messages, you only need to fill a few special registers with the right values in order to indicate to the PLC which nodes you want to communicate and which registers of these slaves nodes you want to read/write.
In this example we will:
Master PLC reads D0~D49 (50 words) on PLC ID1 and stores the data on D100~D149 of his internal memory.
Master PLC reads D0~D49 (50 words) on PLC ID20 and stores the data on D150~D199 of his internal memory.
Master PLC writes the values of his D200~D249 (50 words) on registers D100~D149 of the PLC ID1.
Master PLC writes the values of his D200~D249 (50 words) on registers D100~D149 of the PLC ID20.
Increments D200 and D249 (these values will be wrote on ID1 and ID20).
On the slave’s side, we only have to configure the communication (ASCII/RTU, baudrate, data bits, parity, stop bits) and a different node number to each slave.
NODE 1:
NODE 20:
Here you have the programs of the Master PLC and both Slaves and also a pdf where you can find which registers you have to configure in order to read/write each one of the 32 Slaves.
Now you have seen all the required steps to configure a powerful data exchange between a Master PLC and up to 32 Modbus slaves with just a few program code lines, enjoy it!
Another successful application from our Netherlands distributor Innomotion.
This time is a Woodcutting / Profiling machine with 11 axis control!
As you can see on the picture our partners use 7 VFD-E drives for transportation and high speed spindle, and 4 servodrives ASDA-A2 400W for the cutting/profiling.
Everything controlled by central CPU with Master CANopen module (DVPCOPM-SL).
Via the PC Cad drawings are imported to the Machine and machine settings are executed. The PLC is controlling all the I/O and servo’s for the motion.
In this machine the wooden boards for the stairs are cut to length , width and angle on front and end of the board. The PC software is written in Labview.
I hope you like it!
And with some luck, you can use it as inspiration for your next project!
This time, the problem comes because of the big number of drives needed for the application.
Up to 68 Slaves to be controlled by a PLC, and even in Modus the theoretic limit is 128 nodes, the ones who are really in the field should know than more than 32 nodes means big troubles.
According to this, we recommend to our customer to use CANOpen in two different CANOpen Networks of 34 slaves each.
See the below picture with the network configuration
Just let you know that it wasn’t easy, but is working, thanks for the great technicians of our Turkish distributor FastLTD.
Did you already test our DVPSCM12-SL?
If not, I don’t know what are you waiting for!
The DVPSCM12-SL is the magic device that allows you to communicate with any RS485 based device.
And we’re no talking only about PLC’s or HMI’s… We’re talking about inverters, HVAC, Electrical power analayzers or whatever your customer decides that needs data.
So according to the success of his product, we decide to do something similar more focus in Building Automation, and we decide to develop a communication module for Bacnet
As you can see in this presentation, our device is able to communicate with the main HVAC brands (Johnson Controls, Honeywell, Siemens, Delta), And we demostrated on the below videos. BacNet examples
For further information don’thesitate to download the manual of this device on our web site. DVPSCM52-SL Manual
Ethernet function of DVP12-SE PLC
Delta Industrial Automation 