System words %SW160 to %SW167 indicate M580 local  IO module health.
These words detect errors for racks 0 through 7.
System words %SW160 to %SW167 are associated, respectively, to racks 0 to 7.

Bits 0 to 15 of each of these words are associated with the modules located in positions 0 to 15 of these racks.

The bit is at 0 if the module has a detected error, and at 1 if the module is operating correctly.
Example: %SW163.5 = 0, the module located in position 5 on rack 3 has a detected error.

%SW185 to %SW339  IOHEALTHij I = 1..32,  j= 1..5 Health Bits of the  S908 drops

Initial State   0

Words %SW185 to %SW339 are associated with drops 2 to 32. Each drop has 5 words assigned to the main and up to four configured extension racks:

• %SW185: module health bits of the S908 drop 2, rack 1 (main).
• %SW186: module health bits of the S908 drop 2, rack 2 (extension).
• %SW187 module health bits of the S908 drop 2, rack 3 (extension).
• %SW188 module health bits of the S908 drop 2, rack 4 (extension).
• %SW189 module health bits of the S908 drop 2, rack 5 (extension).
• ...
• %SW335: module health bits of the S908 drop 32, rack 1.
• %SW336: module health bits of the S908 drop 32, rack 2.
• %SW337 module health bits of the S908 drop 32, rack 3.
• %SW338 module health bits of the S908 drop 32, rack 4.
• %SW339 module health bits of the S908 drop 32, rack 5.

NOTE:
The Quantum drops support only two racks and system words for rack 3, 4, and 5 are not used.
The 800 Series I/O drops support up to five racks.
Bits 0 to 15 of each of these words are associated with the modules located in positions 16 to 1 of these racks.
The bit equals 0 if the module is inoperative and equals 1 if the module is operating correctly.

Example: %SW185.5 = 0: the module located in S908 drop 2, main rack, slot 11 is inoperative.
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The words %SW548 to %SW640 are used to describe the communication status of the S908 drops. 3 status words are used for each drops:

• %SW548: displays the global communication status for drop 2:
  • %SW548.15 = 1, communication operating correctly.
  • %SW548.14 = 1, communication on cable A operating correctly.
  • %SW548.13 = 1, communication on cable B operating correctly.
  • %SW548.11 to %SW548.8 = lost communications counter.
  • %SW548.7 to %SW548.0 = retry totalizer counter.
• %SW549: is the global error totalizer counter for cable A drop 2:
  • most significant byte: frame detected error counter.
  • least significant byte: no response counter.
• %SW550: is the global error totalizer counter for cable B drop 2:
  • most significant byte: frame detected error counter.
  • least significant byte: no response counter.

The words:

• %SW551 to %SW553 are assigned to S908 drop 3.
• %SW554 to %SW556 are assigned to S908 drop 4.
• ...

%SW638 to %SW640 are assigned to S908 drop 32.
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Ethernet RIO Drop Module Health bit status is part of the Drop Device DDT that Unity creates.
There is no system word.

The two Device DDT elements for the BMXCRA312x0 Drop are called IO_HEALTH_RACK0 and IO_HEALTH_RACK1
The two Device DDT elements for the Quantum 140CRA312 Drop are called IO_HEALTH_RACK1 and IO_HEALTH_RACK1

Bits 0 to 15 of each of these words are associated with the modules located in positions:
16 to 1 of the 140 CRA 312 00 drop module
15 to 0 of the BMX CRA 312x0 drop module

The bit is set to 0 if the module has detected an error.
It is set to 1 if the module is operating correctly.