Publication 1747-RM001G-EN-P - November 2008
SLC Communication Channels 13-21
Note that all 164 words are updated during each end-of-scan. The following
table describes possible states of the DH+ node address and the value written
to the Global Status Word (S:99).
• If the Global Status File (S:100-S:163) is working and then Channel 1 is
disabled, the entire Global Status File is zeroed out.
• If the Global Status File (S:100-S:163) is working and bit S:34/4 is reset,
the entire Global Status File is zeroed out except for the one word
corresponding to the Channel 1 DH+ node address.
• If the Global Status File (S:100-S:163) is working and then a DH+ link
error occurs, the entire Global Status File is zeroed out. If the SLC 5/04
processor recovers from the error on its own, then the Global Status
File updating resumes automatically.
• If the Global Status File (S:100-S:163) is working and then a user
program with a System Status File of less than 164 words is
downloaded, the SLC 5/04 processor detects this before any further
updating of the Global Status File is attempted. In other words, no
corruption of the user program results even if all other criteria are still
met to support the GSW reception table feature.
Table 13.6 DH+ Node Address State
State of the DH+ Node Address Value written into S:99 by the SLC 5/04
processor
Device is not active on the DH+ link 0x0000
Device is active on the DH+ link, but not
sending GSW bytes in its Token Pass
0x0000
Device is active on the DH+ link and is
sending 1 byte of GSW data in its Token
Pass
High byte is set to 0x00; Low byte is set
equal to 1 byte of GSW data
Device is active on the DH+ link and is
sending 2 bytes of GSW data in its Token
Pass
High byte is set equal to the second byte;
Low byte is set equal to the first byte (or
High and Low bytes are set equal to each
other)
Device is active on the DH+ link and is
sending 3 or 4 bytes of GSW data in its
Token Pass
High byte is set equal to the second byte;
Low byte is set equal to the first byte, and
the third and fourth bytes are ignored
TIP
The SLC 5/04 processor maintains a working Global Status
Word table regardless if Channel 1 DH+ Active Node Table
operation is enabled, (by setting S:34/1).
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