This Mbus network is the Meter Bus system as defined in the European Standard EN13757. The network consists of a Master device and one or more Slave devices interconected using twin wire cabling. The Master device controls the communications over the whole network.
In the case of a network using the Jace, the Jace is connected directly to the Master device via an RS232 or TCP/IP connection. Master devices which communicate to the Jace via a TCP/IP connection usually require setup with their own propriety tools / web interface to run at a given Mbus baud rate speed for the twin wire bus. (TCP/IP Masters will typically run at one fixed baud rate therefore limiting the baud rate at which devices can be reached on).
Master devices which communicate to the Jace via a Serial connection, will usually support multiple baud rates for the twin wire bus. These devices will usually pass through baud speed changes from the Jace, and therefore facilitate the use of multiple baud rates on a single twin wire mbus. All devices should be compatible with a baud rate of 300 baud, however in pratice this has not been found to be consistently applied.
The Jace takes on the control functions of the Master device and it is capable of setting up and interrogating the network for information.Note: Only one Master device can exist on the network and the slave devices can be between 1-250 in number, using primary addressing. Subject to the limitations placed on the communication network by EN 13757.
Where slaves support secondary addressing it is possible to use the driver to communicate with them via this mode. Due to the additional communications overhead this introduces, primary addressing is recommended whenever possible.
Because of the nature of this network it is recommended that before connecting slaves into the system a check is made to ensure that all slaves have primary addresses allocated to them and that they are unique. If the primary address of a slave is unknown then it must be connected into the network as the only slave (point to point) and the "Get Single Connected Device Data" action at network level carried out, which will result in the slave responding with its primary address (refer to the Network section). If the slave has to be given a new primary address then this can be carried out using the "Assign Address" action at network level but the unit must be connected in "point to point" configuration (refer to the Network Manager section).
The core object for the driver is the MBusNetwork component. Place this object under the 'Drivers' component of the station. Once installed, the object is set up like any other serial port driver.
When the MBusNetwork is started for the first time, ensure that the serial configuration is set to that compatible with the interface device. Typically this may be...
Baud Rate=Baud300, Data Bits=Data Bits8 , StopBits=Stop Bit1, Parity=Even, and the Port Name set to the port that the interface device is connected to.
It is important that the baud rate of each device is setup correctly as the baud rate of the serial communications will change depending on which slave device is being communicated with. The baud rate is used to calculate part of the TX / RX timeouts, and it therefore must be correct.
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