Chapter 27
The Status File
27–25
Address
Description
5/02
5/01,
Fixed
S:13
and
S:14
Math Register
Read/write. Use this double register to produce 32 bit signed divide
and multiply operations, precision divide or double divide operations,
and 5 digit BCD conversions.
These two words are used in conjunction with the MUL, DIV, DDV,
FRD, and TOD math instructions. The math register value is
assessed upon execution of the instruction and remains valid until the
next MUL, DIV, DDV, FRD, or TOD instruction is executed in the user
program.
An explanation of how the math register functions is included with the
instruction definitions.
If you store 32bit signed data values (example on page 20-6), you
must manage this data type without the aid of an assigned 32bit data
type. For example, combine B10:0 and B10:1 to create a 32bit
signed data value. We recommend that you keep all 32bit signed
data in a unique data file and that you start all 32bit values on an
even or odd word boundary for ease of application and viewing. Also,
we recommend that you design, document, and view the contents of
32bit signed data in either the hexadecimal or binary radix.
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When an STI, I/O Slot, or Fault Routine interrupts normal execution of
your program, the original value of the math register is restored when
execution resumes.
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S:15L
Node Address
Read/write. This byte value contains the node address of your
processor on the DH-485 link. Each device on the DH-485 link must
have a unique address between the decimal values 0 and 31. To
change a processor node address, write a value in the range of 1-31
using either the EDT_DAT or NODE_CFG functions of your HHT, then
cycle power to the processor.
The default node address of a processor is 1. The default node
address of APS or the HHT programmer is 0. To provide runtime
protection from inadvertent EDT_DAT alteration of your selection,
program this value using a MOV and MVM instruction in an
unconditional rung as shown below. Example, showing runtime
protection of node address 3:
MVM
MASKED MOVE
Source
N7:0
Mask
00FF
Dest
S:15
MOV
MOVE
Source
3
Dest
N7:0
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