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Bit number
Contents 0011000000111001
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
1. First take the absolute value (12345) and convert to unsigned binary:
Bit number
Contents 1100111111000110
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
2. Next take the complement:
Bit number
Contents 1100111111000111
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
3. Finally add one:
Reverse the procedure to convert negative signed binary data to decimal.
3-3 IR (Internal Relay) Area
The IR area is used both as data to control I/O points, and as work bits to manipu-
late and store data internally. It is accessible both by bit and by word. In the
C200HX/HG/HE PC, the IR area is comprised of words IR 000 to IR 235 (IR
area 1) and IR 300 to IR 511 (IR area 2). Basic instructions have somewhat long-
er execution times when they access IR area 2 rather than IR area 1.
Words in the IR area that are used to control I/O points are called I/O words. Bits
in I/O words are called I/O bits. Bits in the IR area which are not assigned as I/O
bits can be used as work bits. IR area work bits are reset when power is inter-
rupted or PC operation is stopped.
Area Range
IR Area 1
I/O Area 1 IR 000 to IR 029
Group-2 High-density I/O Unit Area 1
and B7A Interface Unit Area
IR 030 to IR 049
SYSMAC BUS and CompoBus/D Output
Area
IR 050 to IR 099
Special I/O Unit Area 1 IR 100 to IR 199
Optical I/O Unit and I/O Terminal Area IR 200 to IR 231
Work Area IR 232 to IR 235
IR Area 2
I/O Area 2 IR 300 to IR 309
Work Area IR 310 to IR 329
Group-2 High-density I/O Unit Area 2 IR 330 to IR 341
Work Area IR 342 to IR 349
CompoBus/D Input Area IR 350 to IR 399
Special I/O Unit Area 2 IR 400 to IR 459
Work Area IR 460 to IR 511
I/O Words If a Unit brings inputs into the PC, the bit assigned to it is an input bit; if the Unit
sends an output from the PC, the bit is an output bit. To turn ON an output, the
output bit assigned to it must be turned ON. When an input turns ON, the input bit
assigned to it also turns ON. These facts can be used in the program to access
input status and control output status through I/O bits.
Input Bit Usage Input bits can be used to directly input external signals to the PC and can be used
in any order in programming. Each input bit can also be used in as many instruc-
tions as required to achieve effective and proper control. They cannot be used in
IR (Internal Relay) Area Section 3-3