Step 3: Specify Master Memory Area - Automation Direct DL05 User Manual

The number of bytes specified also depends on the type of data you want to obtain. For
example, the DL05 Input points can be accessed by V-memory locations or as X input
locations. However, if you only want X0 – X27, you'll have to use the X input data type
because the V-memory locations can only be accessed in 2-byte increments. The following
table shows the byte ranges for the various types of DirectLOGIC products.
DL05 / 06 / 205 / 350 / 405 Memory
V-memory
T / C current value
Inputs (X, SP)
Outputs
(Y, C, Stage, T/C bits)
Scratch Pad Memory
Diagnostic Status
DL330 / 340 Memory
Data registers
T / C accumulator
I/O, internal relays, shift register bits, T/C
bits, stage bits
Scratch Pad Memory
Diagnostic Status(5 word R/W)

Step 3: Specify Master Memory Area

The third instruction in the RX or WX sequence is a
Load Address (LDA) instruction. Its purpose is to
load the starting address of the memory area to be
transferred. Entered as an octal number, the LDA
instruction converts it to hex and places the result in
the accumulator.
For a WX instruction, the DL05 CPU sends the
number of bytes previously specified from its memory
area beginning at the LDA address specified.
For an RX instruction, the DL05 CPU reads the
number of bytes previously specified from the slave,
placing the received data into its memory area
beginning at the LDA address specified.
NOTE: Since V-memory words are always 16 bits, you may not always use the whole word. For example, if
you only specify 3 bytes and you are reading Y outputs from the slave, you will only get 24 bits of data. In
this case, only the 8 least significant bits of the last word location will be modified. The remaining 8 bits are
not affected.
Appendix K: Introduction to Serial Communications
Bits per unit
16
16
8
8
8
8
Bits per unit
8
16
1
8
16
DL05 Micro PLC User Manual, 6th Edition, Rev. A
Bytes
2
2
1
1
1
1
Bytes
1
2
1
1
10
4 0 6 0 0
Starting address of
master transfer area
LDA
O40600
V40600
MSB
15
V40601
MSB
15
1
2
3
4
E
6
7
H
9
(octal)
10
K
12
13
LSB
14
0
LSB
A
0
B
C
D
K–11