CI867 with MOXA NPort for
We need to configure CI867 to access Modbus RS485 devices connected via 8 port MOXA NPort 5650 (Modbus Serial to TCP Converter). The problem is that when we configure Gateway under CI867 it only asks for IP address under which we assign IP of MOXA Ethernet Port, Modbus slaves can be directly added under Gateway with their position as Device IDs but there is no option of putting the Moxa Serial Port Number (1-8) and then the Slave ID.
Considering we have 8 serial devices on all 8 ports of MOXA.
Can CI867 access Slaves without MOXA Port numbers?
Can we have devices with similar Modbus IDs as MOXA ports are different?
Whats the best way of configuration keeping in view that Serial device is Slave, should MOXA be put as TCP Server or Client, Should CI867 act as Master or Slave (how to configure it as Master or Slave)?
You will need to refer to the MOXA documentation for specific instructions. Install the MOXA software onto your PC, connect the PC to the convertor and run the program to configure the interface.
The MOXA is neither a master nor a slave - it is simply a convertor. The CI867 is a Modbus TCP Master, the MOXA should make the RS485 Serial devices appear to be TCP slaves to the CI867. The MOXA unit is also responsible for mapping TCP supported commands to compatible Modbus Serial commands. Modbus Serial devices typically have a limited set of data that can be transferred over a serial link.
This question was already asked this week:
I will only add that You shouldn't connect 8 RTU slaves to one gateway, as stated in the manuals:
Also You must understand that CI867 is a Modbus TCP/IP Master (or slave, but in this case a master) and as such it does not care for gateway port numbers etc. It's Gateway function to convert TCP/IP to RTU and the other way around and route the signals from on IP to more then one slave.
Hope this helps,
Source: 3BSE035982_AC 800M Communication Protocols
In this case, CI867 card will act as Modbus TCP/IP Master, and the Moxa Switch will act as Modbus TCP/IP Slave and Mosbus RTU Master and the field devices will act as Modbus RTU Slave.
The Modbus RTU slaves are identified by its Unique Slave ID by CI867 card (Modbus TCP/IP Master) and not by its port numbers.
COnsider this as example, CI867 IP: 192.168.10.1
Moxa Switch IP: 192.168.10.100
Field Modbus RTU Slave Devices ID(Meteres/PLC): 3
If CI867 card position in the CEX bus is : 1
Then enter the Gateway IP as: 192.168.10.100 (Same as Moxa Switch)
Then Insert the Modbus Serial slave in the position: 3
Then its channel shall be: 1 (CI867 card position)
Then its Partner shall be: 1.1.3 (Ethernet.GatewayPosition.ModbusSerialSlavePosition)
Moxa N Port is a Device server (Virtual Serial Port option on TCP/IP Network). We can simply say this as "Interface converter" which coverts RTU to TCP (Serial to Ethernet) or vice versa. We can access the serial devices from anywhere on TCP/IP network. To access each serial device from remote, you may need to give IP address of Moxa N Port device with TCP/IP Socket Port number. (eg- 192.168.10.1:30) or you may need access thru virtual serial port created using Moxa Software.
But here you have Modbus RTU (RS485) Slave Devices and CI867 Modbus TCP Master Device. Actually here you required is "Protocol Converter" (to convert from Modbus RTU to Modbus TCP/IP or vice versa) and not just the "Interface Converter". MGate of MOXA - could be the best option.