Connecting a slave device with an M-bus interface, the MR-0158 submodule

M-bus 01.03.2020 09:25 04.03.2020 17:53

The MR-0158 submodule contains the circuitry of the master physical interface for the connection to the M-bus (for a more detailed description of the M-Bus, see the previous chapter). This bus is the most frequently used for communication with heat meters, etc.

It is designed for systems of the series TC700, Foxtrot, TC650, TEMPO, etc., equipped with a serial interface for the submodules.

The length of the bus is limited by a maximum voltage drop in each wire (it should not exceed 0.5 V), which depends on the consumption of slave modules in an idle state (the number of modules x 1.5 mA) and the wire cross-section. If the line is overloaded, the M-bus fuse disconnects the built-in converter for approx. 1second, and then try to activate it again to its normal function. This condition is signalled by a DCD signal (possibly also CTS) log.0. After the overloading subsides, the fuse itself returns to its normal function.

The module makes it possible to excite the standard M-Bus line with 20 slave stations. The M-Bus power supply is galvanically isolated from other circuits.

The CH2 interface (designed for being mounted with removable submodules - including the MR-0158) is terminated in the Foxtrot basic module connectors in accordance with the module type, see the following figures.

 


Fig. 1. Connecting M-Bus meters to the CH2 interface (MR-0158) of the modules CP-10x6 and CP-10x8

 

Notes:

  1. Up to 20 metering devices can be connected to the interface fitted with the MR-0158 submodule.

  2. A maximum length of the cable (the M-Bus) is by default 350 m; if a maximum drop < 0.5V on each wire is observed, the total length of the line can be up to 4 km.

  3. The recommended cable is a standard telephone type, with the 0.8 mm diameter, better shielded (shielding should be connected on the side of the Foxtrot module to the protective earth PE). It is also recommended to use the J-Y(St)Y 1x2x0.8 cable.

 

 


Fig. 2. Connecting M-Bus meters to the CH2 interface (MR-0158) of the modules CP-10x0, CP-10x4, CP-10x5

 

Notes:

  1. Up to 20 metering devices can be connected to the interface fitted with the MR-0158 submodule.

  2. A maximum length of the cable (the M-Bus) is by default 350 m; if a maximum drop < 0.5 V on each wire is observed, the total length of the line can be up to 4km.

  3. The recommended cable is a standard telephone type, with the 0.8 mm diameter, better shielded (shielding should be connected on the side of the Foxtrot module to the protective earth PE). It is also recommended to use the J-Y(St)Y 1x2x0.8 cable.