Cutler-Hammer D320 PLC, User Manual

Page: 62 / 258

50
D320 PLC User's Manual
6. L (Link) register (Can be bit, word, or double word)
A special memory area which holds shared data when the D320 PLC is on a Link Network
with other D320 PLC's. Refer to the D320 Link Network User's Manual for detailed
information on the L registers.
Each type of register is used for a variety of purposes. The register used will be determined by the type
of function being performed.
1. When a calculation or input value exceeds 65,535 ($FFFF), use double word instructions
which can store and calculate values over 65,535 in the K, M, R, and W registers. When a
double word instruction is used, it can represent values up to 4,294,967,295 (2
32
).
2. When a value needs to be stored even through a loss of system power, use the K or W area.
The K and W areas are preserved unless specifically erased. The W area is erased by program
downloads or special commands.
3. For bit operations, such as setting, resetting, shifting, or rotating use the M, K, or R registers.
You cannot perform bit operations on W registers.
4. The Set Value of timers and counters is stored in a special area of the W registers, W2048 to
W2303. These values can also be addressed using register type SV. The Set Values are then
referenced as SV000 to SV255.
5. The Present Value of timers and counters is stored above the Set Values in the W registers,
from W2304 to W2559. These values can also be addressed using the PV designation, PV000
to PV255. The Present Value is maintained in the Stop state. It is also retentive—the value is
maintained through loss of power.
Internal/External Address Designation
•
The memory address designation types are R, L, M, K, F, W, SV, PV, SR, and TC.
Types F and TC can only be used to designate bits.
Types W, SV, PV, and SR can only be used to designate words.
Types R, L, M, and K can be used for either bits or words.
•
A bit address is composed of a character (R, L, M, K, F), a three digit word address (000 to
127), a decimal point, and a bit address (0 to 15). The timer/counter contact is represented by
the TC label followed by three digits. The three digits indicate the channel number of the
timer/counter (TC000 to TC255).
•
A word address is composed of a character (R, L, M, K, W) and a four digit number (i.e.
W0000 to W2047). Special areas of word memory have alternate designations. For example,
words W2560 to W3071 are also referred to as the System Registers, and can be represented
as SR0000 to SR0511.
•
The bit address indicates an On (1) or Off (0) state. The word address is composed of 16 bits
that holds data values of 0 to 65,535. The double word address is composed of 32 bits that
holds data values of 0 to 4,294,967,295.