Siemens SIMATIC TIWAY 1 - Manual (Page 67)

CONFIGURING THE HOST COMPUTER PORT
UNILINK HOST ADAPTER 3–9
USER MANUAL
D The host computer must wait for the adapter response for the command
issued, before another command can be issued. This command/response
sequence, illustrated in Figure 3–8, ensures that the response matches
the command.
D It is designed to work with a wide range of ASCII host devices, from
ASCII terminals to intelligent workstations.
D It supports a subset of the ASCII character set, “:”, “;”, “0–9”, and “A–F”.
The adapter will ignore all other ASCII characters between the ending
semicolon delimiter and the next beginning colon delimiter, so the host
computer can use these characters for routing control.
D It is easier to implement than the BDLC protocol, but it is also much
slower since the data is transmitted as ASCII characters requiring two
bytes for each data value. For example, the hexadecimal value:
0E hex
""
/ \ becomes
30 45 (ASCII characters “0” and “E”)
More detailed specifications are given in Appendix A.
Host
Computer
NITP Host
Command
Network
Response
UNILINK
Host
Adapter
Figure 3–8 NITP Command/Response Sequence