adccommunitymod (AutomationDirect) asked a question.
Created Date: July 20,2014
Created By: Lloyd M
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I have never implemented Modbus, I think I understand the concepts (at a high level) but am sure I will miss something (or many things).....So any guidance is appreciated... The project is simply, I have a Do-More CPU with an Ethernet Port in a DL-205 four slot base with two 16 input cards. 24 of the 32 input are connected to the status outputs from the security/access control system. My customer need to see the status of the 24 inputs on on their SCADA automation system. I have been given a fixed IP Address, Subnet Mask, Gateway, and the Modbus/DNP Server Address (99). Do I not need an IP address for the PLC and the SCADA (Server/PC)? After reading the help file for the MWX and MRX instructions...... LOST! Do I really only need the MWX instuction? THANK-YOU.........
Created Date: July 20,2014
Created by: BobO
MRX and MWX are for when the PLC is acting in the master role, but normally a SCADA system is the master, so you shouldn't need them. Just copy the I/O data into one of the Modbus memories served by the builtin Modbus/TCP server (MI, MC, MHR, MIR) and read from the SCADA.
Please note that Modbus addresses start at 1, whereas Do-more is 0-based. So even though we have an MI0, it isn't addressable from the Modbus server.
Created Date: July 20,2014
Created by: Lloyd M
Thank you.....That's easy....
Where do I set the Modbus/DNP Server Address to '99 ' ?
Created Date: July 20,2014
Created by: Do-more PE
You shouldn't need the Modbus/DNP Server Address in the PLC. This is typically used for a MODBUS TCP to MODBUS RTU gateway devices in order to specify which serial slave device you are targeting. PLC's typically assume a Modbus/DNP Server Address of 99.
Created Date: July 20,2014
Created by: BobO
Actually the Modbus/TCP server ignores the address, so we don't even let you specify it.
Created Date: July 30,2014
Created by: Lloyd M
Worked Perfect - First Time
MI/MC so simple........
Thank-you
Created Date: July 20,2014
Created by: Lloyd M
I have never implemented Modbus, I think I understand the concepts (at a high level) but am sure I will miss something (or many things).....So any guidance is appreciated...
The project is simply, I have a Do-More CPU with an Ethernet Port in a DL-205 four slot base with two 16 input cards. 24 of the 32 input are connected to the status outputs from the security/access control system.
My customer need to see the status of the 24 inputs on on their SCADA automation system.
I have been given a fixed IP Address, Subnet Mask, Gateway, and the Modbus/DNP Server Address (99).
Do I not need an IP address for the PLC and the SCADA (Server/PC)?
After reading the help file for the MWX and MRX instructions...... LOST!
Do I really only need the MWX instuction?
THANK-YOU.........