RUNMODE xCP Modbus Slave loadable blocks for S7-300/-400 Page 2 of 20 RUNMODE S7 XCP MODBUS RTU SLAVE FEATURES. EXAMPLE USING CP341 ASCII. MODBUS RTU with CP341. Manual:” Loadble driver, Modbus RTU, CP341 master. Telling the slave that you are needing data from this slave (slave address), the.
Hello Ajith; I have done projects like yours and I can give these recommendations: In first stage, connect the master to only one slave at a time. Phisical connections on the cable are crucial, they must be checked slave by slave, also the slave must be configured properly, and you must check the DONE and NDR bits of the Send and RCV functions to make sure they acknowledge transmissions. Remember that if you are using a single cable to connect master and all slaves then they must all have the same interface parameters (speed, parity, stop bits.). Once all 4 slaves work individually and you are sure they are all compatible, you must build a calling function in the master that will synchronize the pairs of SEND/RCV functions for each slave; that is, wait for the NDR bit of the RCV function for slave no.
1 before calling the SEND function for slave no.2. Do it cyclically (slave no.4, slave no.1, slave no.2.) so the processor has confirmation of each transmission before going on to the next. This slows the exchanges a bit but they are then all reliable. Hope this helps, Daniel Chartier.
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Modbus Rtu Wiring
APPLICATION and System Requirements Use the CAS Modbus Scanner to find the correct port settings and the correct slave address. The tool automates the process of trying all the combinations and reports the results. The tool works for RS232 and RS485 by allowing you to search for a single device or multiple slaves. To connect to a RS485 network from your laptop you simply need a USB-to-485 converter. Windows 2000, XP, Vista, Windows 7 (32bit or 64bit), Windows 8 (32bit or 64bit), or Windows 10(32bit or 64bit). 10mb of free space.
Modbus Master Slave
BACnet MSTP requires an RS485 port. You will need to purchase a USB to RS485 converter (Insert Abacus Product recommendation and link here).