On this way for every register I need to call MASTER FC. For example, reading/writing multiple registers may help reduce the total number. So reading 200 bytes (even I do need 30) is not such a problem with this speed, or it is?Ĭreate a loop inside SCL, inside I change register number and my DB_Area adress(place where I store data) everytime I get done and no error signal on pisitive edge. Modbus is a request-response protocol implemented with a master-slave. My baundrate is 9600, so thats 1200 bytes per sec, that is good speed. In that case I just need to use once MASTER function inside PLC and point on starting register and take a lot of bytes. Inside PLC create huge DB which covers all registers I need and + spares between needed registers. The following is an example of a Modbus RTU request for obtaining the AI value of the holding registers from registers 40108 to 40110 with the address of the device 17. Productivity Suite Tag Types (Data designation or source) 16. Modbus 984 Addressing (Zero Based) Modbus 984 Addressing. Bit fields in integers Some manufacturers store multiple bits in a 16-bit register, instead of as individually adressable bits. Each table has its own offset, respectively: 1, 10001, 3001. Boolean System Read Only (SBR) Modbus Client/Master Support (Using MRX and MWX Instructions) Continued. 32-bit registers Enron Modbus allows larger registers where you can store 32 bits in a single register (instead of two consecutive 16 bit registers).

Now my task is to read multiple registers with address as follows:Ĭan you please tell me what's the correct approach in this cases: The difference between these two quantities is offset. I'm able to read data from the slave with my master s7-1200 PLC.

Modbus read multiple registers