In the current market, the superior features of Delta's DOP series touchscreens have made them popular with many users, and their market share is constantly increasing. However, due to historical reasons, many control devices previously had poor openness and weak communication capabilities. Some manufacturers, for security reasons, did not use publicly available communication protocols, and many product designs did not consider communication connections in the initial stages. All of these factors made communication connections between touchscreens and touchscreens very difficult. Now, market demand has driven technological advancements, and product upgrades have led to more and more products using high-end controllers, from microcontrollers to PLCs to PCs, with increasingly stronger communication capabilities. Microcontroller systems are also beginning to integrate communication protocols, thus ensuring a broad application prospect for touchscreens. The following is an introduction to the communication capabilities of Delta's DOP series HMIs: Delta's DOP A series products integrate two serial communication interfaces (as shown in the figure), labeled COM1 and COM2 respectively. COM1 is RS232, and COM2 is RS232/RS485 (optional). The AE series provides three serial communication ports; the A series DOP will be used as an example for explanation. To enable communication between Delta DOP A-series touchscreens and other external devices, which integrate two serial communication interfaces, besides matching the physical characteristics of the communication ports, all parties involved in the communication must use the same communication protocol. From the OSI seven-layer model, this part belongs to the data link layer (complex communication protocols are also closely related to the network layer), mainly reflected in the information frame transmission protocol (including error control). The information frame transmission protocol includes the following parts: Data link establishment and teardown: synchronization, address confirmation, send/receive relationship, last transmitted information transmission (format, quantity, reception confirmation) Transmission error control (verification) Abnormal situation handling Currently, Delta DOP provides the following methods for communicating with different controllers: 1. Using different manufacturers' own communication protocols. Delta DOP writes different manufacturers' protocols into drivers and integrates them into the ScreenEditor configuration software. For example, Siemens PLC's PPI and MPI protocols; KOYO PLC's K protocol; Omron PLC's Hostlink protocol; Modicon's UniTelway protocol; GE's SNP-X protocol, etc. 2. Uses open protocols. Currently, Delta DOP uses the MODBUS open protocol. The MODBUS protocol is a common language used in electronic controllers. Through this protocol, controllers can communicate with each other and with other devices via networks (such as Ethernet). It has become a common industrial standard. With it, control devices from different manufacturers can be connected to form an industrial network for centralized monitoring. 3. Use Delta DOP macro communication commands. Macros are a major feature of Delta DOP; communication commands can easily connect to other non-standard controllers. Delta DOP series HMI communication example 1. Example: A customer is using Delta DOP for the first time, connecting an A57GSTD to a Siemens S7-200. Connection method: Delta DOP has integrated the Siemens S7-200 series PPI protocol; the user only needs to perform two steps to complete the communication. Step 1: Make a communication cable according to the instruction manual. As shown in the following figure: Communication Fiber Optic Cable Diagram Step 2 In the ScreenEditor software, under [Options] [Set Module Parameters] [General], make the selections as shown in the figure, and then make the settings as shown in [Communication]: Setting Parameter Display 2. Example: One A57STD is connected to one other brand PLC and one OMRON PLC simultaneously. In the software, we can connect to COM2A using Base Port and connect to FX2N using the added Link2 in [Options] [Set Module Parameters] [Communication], and set the communication parameters respectively. 3. Example: One A10TCTD monitors three A57CSTDs, and each A57CSTD is connected to one Delta PLC. Connection Instructions: The connection method between A57CSTD and PLC is the same as in Example 1, and will not be repeated. The key is how to connect A10TCTD and A57CSTD. As shown in the following figure: Connection Diagram of A10TCTD and A57CSTD Since Delta DOP supports the open MODBUS protocol, we can connect via MODBUS. Set A10TCTD as the master screen, select MODBUS ASCII (Master) as the PLC type, and assign station number 10. Set A57 as the slave screen, sequentially as 1#, 2#, 3#, and select MODBUS ASCII (Slave) as the PLC type, simultaneously setting the HMI station numbers to 1, 2, and 3 respectively. Through the RS485 communication port of each HMI, A10 can monitor any A57. The number can be expanded to 255 units. 4. Example: The PC running KingSCADA software can read and write the $ and RCP addresses of 20 DOP HMIs, while the HMIs are connected to the S7 CPU224. Connection instructions: Considering that the HMI only uses one RS485 communication port, an RS232/RS485 conversion module is added to each HMI; in this example, ADAM4520 (Advantech) is used. The CPU 224 is connected to the HMI COM1 through the ADAM4520. Twenty HMIs connected to KingSCADA via an ADAM4520 COM2 interface are configured, as shown in the diagram below. KingSCADA establishes 20 connected devices, and each HMI has a station number set in the ScreenEditor, making connection establishment easy. The final running screen is shown in the diagram below. 5. Example: Delta DOP communicates with a Delta PLC via macro communication commands. Connection instructions: The Delta PLC itself supports the MODBUS ASCII communication format and uses LRC verification. Below is the program for connecting the DOP to the PLC via communication commands. Other controllers, such as microcontrollers and frequency converters, can also communicate via communication commands. # Communication instructions are only executed if $1.0 is ON: IF $1.0==OFF THEN GOTO LABEL 100 IF $0.0==ON THEN GOTO LABEL 99 # According to Delta PLC's communication protocol, the initial COM2 setting is $0=IITCOM(1,0,0,2,0,6,0) # If initialization is successful, $0.0 will be set to ON; if initialization of COM2 is unsuccessful, the following code will not be executed: IF $0.0==OFF THEN GOTO LABEL 100 CHR($10,":01050500FF00F") $17=D36H $18=AN CHR($30,":010505000000F") $37=OD35H $38=AH CHR($50,":010205000010E") $57=OD38H $58=AH LABEL 99 IF $1.0 == OFF THEN GOTO LABEL 100 # Send 17 bytes of data (totaling $10) to the PLC, store the communication result in $20 $20 = PUTCHARS($10, 17, 500) # Read 17 bytes of data from the PLC, store them starting at $100, and store the success or failure result in $21 $21 = GETCHARS($100, 17, 500) # Send 17 bytes of data (totaling $30) to the PLC, store the communication result in $22 $22 = PUTCHARS($30, 17, 500) # Read 17 bytes of data from the PLC, store them starting at $120, and store the success or failure result in $23 $23 = GETCHARS($120, 17, 500) GOTO LABEL 99 LABEL 100 Delta's DOP touchscreen offers flexible and convenient communication methods, and the above examples can also be combined to achieve richer control modes.