Siemens SIMATIC TIWAY 1 User Manual page 20

2.3.5 The Emulate Host Adapter Modes
There are two modes available that provide an emulation of the TIWAY I Host
Adapter; the MHIU/EHA and the HIU/EHA. These modes are limited to the
base command codes 01 through 08, 20, 21, and FC through FF. The POLL
command, code 03, is not available in the HIU/EHA mode. Both of these modes
will operate with applications software written for the TIWAY I Host Adapter.
The MHIU/EHA can directly replace the TIWAY I Host Adapter in single host
network applications. However, the MHIU/EHA cannot be used in a multiple
host network. The HIU/EHA provides the ability to use TIWAY I Host Adapter
software applications in a multiple host network.
2.3.6 The Standalone Network Manager Mode
The Standalone Network Manager mode operates independent of any host
computer. It controls the TIWAY I network, but cannot accept any host
commands to change any performance parameters. You can use this mode to
implement a multiple host network using applications software written for the
TIWAY I Host Adapter. Only minor changes to the applications software are
needed to process the adapter configuration command. A typical network is
shown in Figure 2–10.
2.4 TIWAY I HOST SOFTWARE SUPPORT
As mentioned in Paragraph 2.3.5, the MHIU/EHA and HIU/EHA modes will
operate with the TIWAY I HOST SOFTWARE products. The MHIU and NM
modes will also work with this product; however, you must enclose the extended
and NM commands in the XPAR subroutine.
UNILINK HOST ADAPTER
USER MANUAL
OPERATION AND APPLICATION
Host
Com-
puter
UNILINK
(SANM)
Figure 2–10 Standalone NM Network
2–10
Host
Com-
puter
UNILINK
(HIU)
UNILINK
(HIU)