Installation manual

Publication 1747-RM001G-EN-P - November 2008
13-20 SLC Communication Channels
• The word in the Global Status File corresponding to the SLC 5/04
processor’s DH+ address will be set to 0x0000 if any thing is done to
inhibit the transmission of the Global Status Word from S:99. This
includes:
– clearing S:34/3, Global Status Word Transmit Enable bit
– placing the SLC 5/04 into a mode other than Run mode or Test
mode
– disabling Channel 1
– an error occurring on the DH+ link to cause the Channel 1 LED to
flash red or go solid red (This could be caused by a duplicate node
address.)
– having an OS400 user program downloaded to the SLC 5/04
processor
• If S:34/3 is not set from the time the SLC 5/04 is powered up, the word
corresponding to its DH+ address in the Global Status File will never
be written to during the end-of-scan.
S:34/4 Global Status Word Receive Enable Bit
Receiving the Global Status Words of other processors on the network is
enabled by setting bit S:34/4 in the status file. If this bit is set (1), the
processor fills in the Global Status File with Global Status Words transmitted
by other processors on the network. If this bit is not set (0), the processor
ignores any Global Status Word activity on the network. This bit is
dynamically configurable and the default setting is zero. Note that transmitting
and receiving Global Status Words are independent of each other.
Keep the following guidelines in mind when using the Global Status Word
Receive Enable bit:
• If this bit is not set, the Global Status File (S:100 to S:163) is not
updated with Global Status Word information being passed on the link.
• An error occurring on the DH+ link to cause the Channel 1 LED to
flash red or go solid red disables Global Status Word receptions. (This
could be caused by a duplicate node address.)
• Global Status File (S:100-S:163) support is enabled when the following
four conditions are met:
– Channel 1 is configured for DH+ protocol communication
– the System Status File is at least 164 words in length
– the Global Status Word Receive Enable bit (S:34/3) is set
– operation on the DH+ link is working (Channel 1 LED is green)
• Global Status Word reception will not occur while downloading a
program.