Slave, Transmitter and Input addressing

The following discusses the allocation of addresses to the slaves on the Modbus

network – including the MTL838C  – and the allocation of addresses for the

transmitters and inputs connected to each MTL838C.

Addressing MTL838C slaves

Modbus allows slave addresses in the range 1 to 247.  JBUS allows slave

addresses in the range 1 to 255.  This is the only difference between the two

protocols.  Since the MTL838C can only have addresses in the range 1 to 31. it will

work equally well with either protocol.

The Modbus address for each MTL838C slave is set via the PC software.  For

reasons of security, it is not possible to set the address of the slave via the

Modbus host.

The address for each RS485 port on the MTL838C may be set from 1 to 255.  This

facility allows the MTL838C to be connected to the same master twice or to two

different masters independently.  There is no restriction regarding simultaneous

communication on both ports. The unit will respond via the port on which it

received the query.