10/6/2009 7:52 AM | |
Posts: 5 Rating: (0) |
Hello Friends,
Is it possible to use Modbus Master on Port-0 of CPU-224? I have One no. of CPU-224 as Modbus Master and 11 no. of CPU-224 as Modbus Slaves. I am using Modbus MBUS_CTRL and MBUS_MSG to assign Port-0 of CPU-224 for Modbus Master. I have Configured Port-0 in Terminal mode for Program Download and Run Mode for Modbus Master with SM0.7 bit. Right now I have only one CPU-224 for my testing so I am trying to Read/Write register values with Modbus Slave software that I havedownloaded from http://www.modbustools.com/. The connection I did are as per attached PDF file. RS-232/485 convrter to PLC connection is Half Duplex. I am unable to read/write the values. With Half Duplex connections Modbus Slave on Port-0 of CPU-224 is working fine. But Modbus Master not working. Am I missing anything to make Modbus Master on Port-0? Is Modbus Slave software OK for my testing? Can any one suggest me the options to make Modbus Master work? I appreciate all your suggestions in advance. Best Regards, Pramod AttachmentModbus Master.pdf (1154 Downloads) |
This contribution was helpful to1 thankful Users |
10/6/2009 10:43 AM | |
Posts: 5 Rating: (0) |
Hello Robster, first question: Did you use Modbus Library for Port 0? And how did you parametrize MBUS_CTRL? Ans: Yes, I have used modbus Library for Port 0. MBUS_CTRL Parameters are Baud=9600, Parity=2, Timeout=1000. Please find attached PDF print of PLC program. second: Did you try PC/PPI serial cable for connection between PC simulation and CPU224? Ans: I am using USB/PPI Multi master cable. In run Mode PLC Port goes to Modbus Master hence the communication via this cable brakes. I have made custom cable to communicate PLC Port-0 to RS232/RS485 converter then to PC serial port. I made the experience that a third party RS232/RS485 converter maybe not working 100% correctly. And the PC/PPI cable is nothing more than a converter. Ans: This converter is working fine if I do PLC Port-0 to Modbus Slave. Actually, the communication is 2-wire half duplex by which Modbus Slave is working fine. Same connections I am using for Modbus Master with only change in PLC code for Modbus Master. I am not sure if 2-wire half duplex connection is OK with Modbus Master. third: What register address you tried to read/write and how did you enter it at MBUS_MSG and what did you enter in simulation software? Ans: Actually, I set VW10=10 in PLC while in terminal mode. then I swith to Run Mode which activates Modbus Master. I am trying to read VW=40001=10 on Simulation software. Please find attached PDF print of PLC program for more details. I hope I have given satisfactory information to your questions. I appreciate your help in advance! Best Regards, Pramod regards AttachmentMod_Master_PLC.pdf (1057 Downloads) |
8/9/2017 1:28 PM | |
Posts: 10 Rating: (0) |
AttachmentModbus Master and slave programs.zip (768 Downloads) |
11/21/2017 2:58 PM | |
Joined: 6/19/2017 Last visit: 9/6/2024 Posts: 8175 Rating: (172) |
New question published by prashant sherikar is split to a separate thread with the subject Don't have the password of plc and plc is in run mode . Best regards |
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