User guide

Health Status
200
890 USE 108 00 August 2001
Checking System’s Health Status
System Health
Status
The Compact Controllers maintain a table in memory that contains vital system
diagnostic information regarding the CPU, I/O, and communications. The following
information explains how Its contents are structured.
The following table lists the vital system diagnostic information that is kept in
memory.
Each status word is 16 bits long, and the status information is conveyed by the
sense of the bits in each word. The illustrations in this map show how the status
information is presented in the status table.
The words in the status table can be accessed in ladder logic using the STAT
instruction. The STAT block displays the bit patterns of the status words in a table
of contiguous 4x registers, the values of which can then be seen in the panel
software.
The register that you specify in the top node of the block is loaded with the current
word 1 bit values, and the number of registers that you specify in the bottom node
are loaded with bit values from the corresponding words in the status table.
For example, if you are interested only in accessing controller status information,
you could specify a register address of 40701 in the top node of the block and a
value of 11 in the bottom node; the bit values of the first 11 words in the status table
are loaded into registers 40701 ... 40711, respectively.
To load the whole status table, specify 184 in the bottom node of the instruction. If
you are not using expanded I/O, you need to specify only 40 in the bottom node to
receive all relevant status information.
Status Word Content of Status Register
1 ... 11 Controller status information
12 ... 15 Health of A120 I/O modules
16 ... 181 Not used
182 ... 184 Global health and communications retry status
Note: Although you can specify either a 0x or 4x register in the top node, we
recommend that you specify a 4x because of the excessive number of 0x registers
that would be required to manage the status information.
Note: You do not have to use the whole status table (184 words).