Siemens SIMATIC TIWAY 1 - Manual (Page 133)

HOST COMMAND SET REFERENCE
UNILINK HOST ADAPTER 5–48
USER MANUAL
should be unique. HIUs function like other secondary devices and
will use one of the available addresses as assigned. Address 00 is
only valid for the default for an MHIU and cannot be specified.
Option–03 = This parameter defines the maximum secondary address for
the network, offering a way to save memory by not allocating
storage for secondary device statistics. The most efficient value
for this parameter is the number of actual secondaries, plus the
number of HIUs, plus some padding for network growth. In
addition, you should set your secondary device addresses so that
they are numbered consecutively. Background Monitor checks
each address beginning at one up to the value of this parameter.
Even though there is not a physical device for a particular
address, it gets checked. You must make sure that all secondary
and HIU addresses are less than this value or they will not be
recognized as valid network components. Values range from 1 to
254 (01 hex to FE hex) and will default to 254.
Option–04 = This parameter defines the maximum amount of memory to set
aside for macro storage in MHIUs and HIUs. This option does not
apply to an adapter configured as a Network Manager only or
adapters in the EHA mode. If this option is not specified, it will
default to 0000 hex or 16 kbytes of memory.
vvvv = 0000 — Reserve 16 kbytes of memory for macro storage.
vvvv = 0001 — Reserve 24 kbytes of memory for macro storage.
vvvv = 0002 — Reserve as much memory as possible for macro
storage. Only 24 kbytes will be reserved in an MHIU and possibly
more than 24 kbytes will be reserved in an HIU.