Beijer Electronics SCOM Protocol EN - Manual (Page 15)

Monitor Addressing
Elektronik-Systeme Lauer, MAEN976 15
4 Monitor Addressing
By default, a Lauer Navigation Monitor supports the standard SCOM addressing
scheme, which allows a total count of 16 monitors within a network. The address of
a monitor is set with four DIP switches. If a SCOM command is sent to a monitor,
the ADR field must contain either the broadcast address 0xFF, or the address of the
destination device set by the DIP switches. To eliminate this limit, a new addressing
scheme is introduced first with Lauer Navigation Monitors.
According to the previous chapter, the width of the ADR field is 1 byte (or 8 bits).
The standard SCOM addressing scheme uses only the lower 4 bits of this field (only
in case of the broadcast address, all bits are used), allowing a maximum of 16 address-
es.
The new addressing scheme, implemented in Lauer Navigation Monitors, uses also
the 4 upper bits. To distinguish between the standard and new addressing scheme,
these bits are called “group bits” or simply “group”. Based on this definition, the fol-
lowing table shows field ADR in more detail:
As shown in the table, a group between 0 and 14 can be specified. Group 15 is not
supported, to avoid address collision with the broadcast address. Thus, together with
the address field, a total count of 15 x 16 = 240 monitors can be connected to one
network.
Monitor grouping is activated only, if the monitor is set up to use the software con-
figured address, instead of the hardware address specified by the DIP switches. If the
monitor uses the hardware address, the group address is automatically set to 0, re-
gardless of the group configuration.
Lauer Navigation Monitor addresses are always given in a dotted notation as
“group.address”. This means, if a monitor belongs to group 7 and its address is 3, the
resulting address will be 7.3, which is 115 (0x73). In the standard mode (i.e. DIP
switch address is used), the monitor address will be 0.3 (or simply 3) for the given
example, because the group bits are set to 0.
If a Lauer Navigation Monitor is configured as remote controller, it addresses always
monitors within its own group. By definition, a Lauer Navigation Monitor cannot
remote control monitors in another group.
Related information
Message Format and Description
ADR bits 7...4 ADR bits 3...0
Group
(0 … 14) Address
(0 … 15)