Communication between Yitong Chuanglian MODBUS to PROFIBUS gateway and Honeywell DCS system

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Communication between Yitong Chuanglian MODBUS to PROFIBUS gateway and Honeywell DCS system [Copy link]

Abstract: This article introduces how to use the MODBUS to PROFIBUS fieldbus gateway to achieve communication between Siemens S7-300PLC and Honeywell DCS system.

1. Composition and implementation method of communication system

Honeywell's DCS system communication uses MODBUS communication protocol, while Siemens PLC's data acquisition communication protocol for central air-conditioning chillers is Profibus-DP. In this system, Siemens PLC (S7-300) serves as the Profibus-DP master station, and the modbus to Profibus gateway YT-PB-01 serves as the Profibus-DP slave station. At the same time, the modbus to Profibus gateway YT-PB-01 executes the MODBUS RTU protocol through the RS485 interface and communicates with the Honeywell modbus master station host computer, so as to monitor and collect data on the temperature, water flow, pressure and other related parameters of the chillers of the central air-conditioning system of the Beijing Garden Museum.

1.1 System Configuration

SIEMENS's CPU315-2DP is used as a Profibus DP master station, and the bus address is set to 2; Yitong Chuanglian's modbus to Profibus gateway YT-PB-01 is used as a PROFIBUS-DP slave station, and the bus address is set to 3; the MODBUS slave station address is set to 1. The system connection diagram is shown in Figure 1:

Figure 1: System connection diagram

1.2. Parameter settings of modbus to Profibus gateway YT-PB-01

The YT-PB-01 modbus to Profibus gateway from Yitong Chuanglian can convert RS232 or RS485 protocol interfaces and supports Modbus RTU protocol. It can also be used as a master or slave of MODBUS. Here we choose Modbus RTU protocol, RS485 interface, and MODBUS slave mode.

The following is the corresponding configuration of the gateway:

1.3. Honeywell host computer MODBUS master station communication settings

Honeywell host computer MODBUS master station selects MODBUS protocol for communication. According to the configuration information already configured in the gateway, set the communication parameters as follows: slave address is 1; baud rate is set to 9600; 8 data bits; 1 stop bit; no parity; other parameters use default values. Please refer to the manual for related operations such as reading and writing data areas. According to the slave station data area settings, the address of the read temperature, pressure and other information should correspond to the address of the master station reading the main station. The MODBUS master station reads the slave station address parameter setting starting from 0.

1.4. PROFIBUS communication data settings

1.4.1. PROFIBUS communication data

1.4.2. Configuration and programming of PROFIBUS master

Open the STEP7 programming software and install the slave GSD file of the Modbus to Profibus gateway YT-PB-01 into STEP7, and then configure it through the GSD file, as shown in Figure 3:

Table 3: PROFIBUS communication data volume settings on PLC (Q address is configured according to actual situation)

After the configuration is completed, compile and save.

Program the analog and digital addresses detected by the PLC to MOVE. For example, if the PLC analog input address is AIW0, then just MOVE AIW0 to PIW256. The master station inquiry time is determined by the DCS host computer system. The gateway responds once for each inquiry from the host computer.

3. On-site pictures

In the future, gateways used to convert between different protocols will play an important role in automation systems. As a universal protocol gateway, the Modbus to Profibus gateway YT-PB-01 has been put into practical use in many projects at home and abroad.