Issue
When using the Modbus RTU and Modbus IP XDrivers it is important to determine which controller and port can support the electrical standards used by the 3rd party device.
Product Line
Andover Continuum
Environment
- Continuum Netcontroller II and bCX1 controllers that have been XDriver enabled.
- XDriver, Modbus RTU, IP, Infilink, Infilink200, B-Link. RS-232, RS-485
- JBUS
Cause
Controller ports and 3rd party devices come in various electrical standards (RS-232, RS-485, RS-422), which ports support the various standards?
Resolution
There are two Continuum Modbus XDrivers:
Modbus RTU: This allows the connection of 3rd party Modbus RTU slaves via the serial data RS-232, RS-485 or RS-422 electrical standards. RS-232 is a point to point connection to 1 device, RS-485 & RS-422 support a bus topology for connection of multiple 3rd party devices.
The Continuum controller will be the Modbus RTU Master and will poll the 3rd party device that must be a slave.
The bCX1-CR controllers have 2 ports that can be configured for Modbus:
Comm1 RS-232
Comm2 RS-232 or RS-485 port
The Netcontroller II controllers support:
Comm1 - RS-232 or RS-485
Comm2 - RS-485
Comm3 - RS-232
Comm4 - RS-422
The ACX57xx controllers support:
Comm1 - RS-485
Notes
An Infilink200 or B-Link may be used to convert RS-232 to RS-485 if required.
The J Bus protocol is a subset of the Modbus protocol and so the Modbus XDriver is used for J Bus Systems.
Modbus IP: The bCX1, ACX57xx and the Netcontroller II all support the Modbus IP protocol that connect via the Ethernet IP connection. This XDriver can be configured to support either Client or Server modes. Although the communication is physically via the Ethernet port, one of the Serial ports is required to be X Driver enabled to load the software, this serial port is then no longer available for other purposes.
This XDriver requires Ethernet X Driver support to be enabled on the port.
NOTE Netcontroller II and bCX1 can have an XDriver ENABLED on more than a one Comms port, however only one IP XDriver should be INSTALLED on each controller, also only one Modbus RTU XDriver should be INSTALLED on each controller. It is possible to INSTALL a Modbus RTU and a Modbus TCP/IP XDriver on a single controller, but it would be very easy to overload the controller, so this setup is only suitable for smaller networks. (note the difference between enabling XDriver support and Installing an XDriver)
See Articles Can multiple Modbus TCP/IP XDrivers be installed on a single 2nd Generation NetController? and BCX Controller can use Comm 1, Comm2, or both ports for Modbus RTU X-Driver
