12. Communication Design Examples 12.7 Communication between PLC and Delta DTB Series Temperature Controller (MODRD/MODWR/MODRW) Control Purpose: z Reading as well as displaying the target value and the present value of the TC by MODRD instruction. z Setting the parameters of the TC as following data by MODWR and MODRW instructions. Parameter Settings for DTB Series Temperature Controller: Ъ If TC can not run normally due to improper parameters, users can set the TC to factory defaults first and then set the parameters according to the above table. The setting steps of DTB series are the same with DTA series TC. Ъ Communication protocol of DTB series is as following: 1.
Supporting MODBUS ASCII/RTU communication protocol. Communication baud rate: 2400, 4800, 9600, 19200, 38400. 2. Supporting function code: 03H to read the contents of register. 06H to write 1 word into register. 10H to write many words into register. 3. Non-supported formats in ASCII mode: 7, N, 1 or 8, O, 2 or 8, E, 2 4. Formats in RTU mode: 8, N, 1 or 8, N, 2 or 8, O, 1 or 8, E, 1. 5. Available communication address: 1 to 255, 0 is broadcast address. Devices:
DVP-PLC Application Examples 12-25 Parameter value Communication address Target temperature 26°C 1001H Upper limit of temperature range 50°C 1002H Lower limit of temperature range 0°C 1003H Output type of alarm 1 The first alarm type 1020H Upper-limit alarm 1 5°C 1024H Lower-limit alarm 1 3°C 1025H Parameter Function Set value C WE: Write-in function disable/enable ON C-SL: ASCII, RTU communication format selection RTU C NO: Communication address setting 1 BPS: Communication baud rate setting 9600 LENGTH: Data length setting 8 PARITY: Parity bit setting N STOP BIT: Stop bit setting 2 UNIT: Temperature display unit °C or ℉ °C Device Function