Step 3: Specify Master Memory Area; Step 4: Specify Slave Memory Area - Automationdirect.com DL05 User Manual

Chapter 4: Configuration and Connections

Step 3: Specify Master Memory Area

1 1
The third instruction in the RX or WX sequence is
a Load Address (LDA) instruction. Its purpose is to
2 2
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
3 3
the accumulator.
For a WX instruction, the DL05 CPU sends the
4 4
number of bytes previously specified from its memory
area beginning at the LDA address specified.
5 5
For an RX instruction, the DL05 CPU reads the
number of bytes previously specified from the slave,
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placing the received data into its memory area
beginning at the LDA address specified.
7 7
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
8 8 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.
9 9

Step 4: Specify Slave Memory Area

The last instruction in our sequence is the WX or RX
10 10
instruction itself. Use WX to write to the slave, and RX
to read from the slave. All four of our instructions are
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shown to the right. In the last instruction, you must
specify the starting address and a valid data type for the
slave.
12 12
• DirectNET slaves – specify the same address in the WX
and RX instruction as the slave's native I/O address
13 13
• Modbus DL405, DL205, or DL05 slaves – specify the
same address in the WX and RX instruction as the slave's
14 14 native I/O address
• Modbus 305 slaves – use the following table to convert
DL305 addresses to Modbus addresses
a A
DL305 Series CPU Memory Type–to–Modbus Cross Reference (excluding 350 CPU)
b B
PLC Memory Type PLC Base Address
TMR/CNT Current
c C
Values
I/O Points
D D
Data Registers
Stage Status Bits
(D3-330P only)
4-16 DL05 Micro PLC User Manual, 6th Edition, Rev. D
Modbus
Base Address
R600 V0
IO 000 GY0
R401,R400 V100
S0 GY200
4 0
MSB
15
MSB
15
SP116
PLC Memory Type PLC Base Address
TMR/CNT Status Bits CT600
Control Relays CR160
Shift Registers SR400
6 0 0
(octal)
Starting address of
master transfer area
LDA
O40600
V40600
LSB
0
V40601
LSB
0
LD
KF201
LD
K64
LDA
O40600
RX
Y0
Modbus
Base Address
GY600
GY160
GY400