Communication has different interpretations in different contexts. After the advent of radio wave communication, communication was simply interpreted as the transmission of information, referring to the transmission and exchange of information from one place to another, with the purpose of transmitting messages. However, in the course of human practice, with the development of social productivity, the requirements for message transmission have continuously increased, thus driving the continuous progress of human civilization. With the development of industrial automation, industrial serial communication has flourished. RS485/RS422 communication, due to its advantages such as simple hardware design, convenient control, and low cost, is widely used in projects such as fire protection, hydrology, automatic water conservancy monitoring, and building control. As engineers and technicians, we often encounter similar problems in practical engineering applications.
2. Product Introduction
The AH10SCM-5A is a serial communication expansion module that supports MODBUS RS-422/RS-485. It can be used as an RS-422/RS485 communication port for PLC mainframes, enabling PLC program upload/download and monitoring via ISPSoft.
3. Function Introduction
Two RS422/RS485 sets are provided;
It has two built-in 120-ohm terminating resistors;
Each communication port can connect up to 32 RS422/RS485 devices;
It can be used as COM3 for uploading and downloading PLC programs;
MODBUS Advanced provides MODBUS fast data exchange functionality;
UD Link provides users with the ability to customize communication protocols and process planning.
4 Control Requirements
Data exchange between CPU530-EN and DVP28SV is achieved through DVP10SCM.
5 System Structure
Figure 1 System Structure Diagram
6. Operating Steps
6.1 Hardware Configuration Steps
STEP 1: Connect COM1 (D+/D-) of the DVP10SCM module to COM2 (RS485+/RS485-) of the DVP28SV host.
STEP2: Set the DVP28SV parameters as shown in Table 1.
Table 1 Setting DVP28SV Parameters
STEP 3: Enable COMMGR.
STEP 4: Click the "Add" button to bring up the "Create Driver" dialog box. First, give the Driver a name you like; the default is Driver1. Then, set the relevant parameters according to the connection method between the PC and CPU530-EN, such as Connection Setup\Type and Communication Setting. In this example, the PC and CPU530-EN are connected via USB, and the PC's COM Port is COM5.
Figure 2 Create Driver dialog box
STEP 5: After completing the above settings, click the "OK" button.
STEP 6: Startup settings, as shown in Figure 3.
Figure 3 Startup settings interface
STEP 7: Open ISPSoft, and set a project name for the project, selecting the PLC model. In this example, the project name is set to DVP10SCM, and the PLC model is AHCPU530-EN.
STEP 8: Select "Tools (T)" >> "Communication Settings (P)".
STEP9: Select the communication channel name and set the station number according to the communication address of CPU530-EN. 0 is for broadcast.
STEP10: Double-click “HWCONFIG” on the left to bring up the “HWCONFIG dialog box”.
STEP 11: Select "Settings" >> "Detection (S)".
STEP12: Detection complete, as shown in the image below.
Figure 4 Detection End Interface
Note: By default, the system will configure D0 to D17 as input devices for the DVP10SCM. Therefore, when implementing data exchange between the AHCPU530-EN and the slave station, please note the following two points:
(1) When using the AHCPU530-EN device, avoid using D0 to D17;
(2) Modify the default configuration of the input device of the AH10SCM module.
STEP13: Double-click the 10SCM module icon to bring up the "Parameter Configuration Dialog Box".
STEP 14: Configure COM1 and COM2 as necessary. In this example, COM1 is set to the default value: station number 247, communication format 9600, 7,E,1,ASCII, RS485, to ensure consistency with the communication format of COM2 of DVP28SV.
STEP 15: After completing the COM1 and COM2 settings, click the "OK" button.
STEP 16: Right-click the 10SCM module to bring up the drop-down list.
STEP17: Select "Smart Module Settings" from the drop-down list to enable SCMSoft.
STEP18: Click "MODBUS Advanced".
STEP 19: Right-click "MODBUS Advanced" and add MODBUS Advanced.
STEP20: Double-click “MODBUS1” to bring up the “Edit dialog box”.
STEP21: In the "Edit dialog box", set the MODBUS advanced name, select the backplane number, slot number, and SCM communication port. After setting, click the "OK" button.
STEP22: Set up data exchange between DVP10SCM and DVP28SV.
STEP23: After completing the settings, click the "" button to bring up the "Select Module" dialog box.
STEP24: Select the backplane, select the slot, and click the "OK" button. The "SCM Download List" will pop up.
STEP 25: After the download is complete, click the "OK" button to close SCMSoft and return to the HWCONFIG screen.
STEP26: Click the button to bring up the "HWCONFIG dialog box".
STEP 27: Click the "Yes" button. Close HWCONFIG and return to the ISPSoft editing screen.
6.2 Software Programming
6.2.1 Preparations before programming
Before writing the program, you need to understand the basic register BR of the DVP10SCM module and learn how to use the TO application instruction to implement programming.
6.2.2 Programming
STEP 1: Right-click "Program" on the ISPSoft screen to bring up the "Create Program" dialog box.
STEP2: Enter the POU name, select the program type, programming language, set the password, and click the "OK" button.
STEP3: Write the program as shown in the figure below.
STEP4: Select "PLC Host (P)" >> "PLC Program Transfer" >> "Download (D)".
STEP 5: Click the "OK" button to stop the PLC and download the program. A progress bar will appear during normal downloading.
STEP 6: After the download is complete, a "Confirmation Dialog Box" will pop up, asking whether to restore the PLC to running state.
STEP7: If you want to run the PLC, click the "OK" button; otherwise, click the "Cancel" button.
6.2.3 Data Analysis
Communication data between DVP10SCM and DVP28SV was collected using data capture software. The data is as follows:
The data read from M0 is as follows:
DVP10SCMaDVP28SV, transmitting message: 01 01 0800 0001 F5 \x0D\x0A
DVP28SVaDVP10SCM, receiving message: 01 01 01 01 FC \x0D\x0A
Data transfer register (transmit message):
Table 1 Description of Transmitted Messages
Receive data register (receive message):
Table 2 Description of Received Messages
7. Conclusion
By utilizing the advanced MODBUS function of the AH10SCM module, it is easy to quickly exchange data with Delta industrial automation products, making communication between automation products more efficient and convenient.
About the author:
Du Lixing, male, born in October 1981, graduated from Lanzhou University of Technology with a major in Electrical Engineering and Automation. He is currently a project manager in the System Integration Department of Delta Electronics in Wujiang, specializing in industrial automation product solution integration and system development. He has 8 years of experience in Delta's industrial automation products and the HVAC and water treatment industries.
