The table below identifies the value ranges for Allen-Bradley PLCs:
|
Allen-Bradley Addressing |
Value Range |
|
Output Image |
O:0 – O:30 |
|
Input Image |
I:0 – I:30 |
|
Status |
S:0 – S:n |
|
Binary |
B3:0 – B3:255 (B3:1/15 [16th bit in element number 1) |
|
Timer |
T4:0 – T4:255 |
|
Counter |
C5:0 – C5:255 |
|
Control |
R6:0 – R6:255 |
|
Integer |
N7:0 – N7:255 |
|
Floating Point |
F8:0 – F8:255 |
|
Network |
x9:0 – x9:255 |
|
User Defined |
x10:0 – x10:255 |
Note: The above addressing scheme is applicable for all Allen-Bradley PLC's, regardless as to the model. (Where necessary (e.g. ControlLogix), the PLC's processor takes care of mapping addresses internally.)
An example of the addressing scheme for Allen-Bradley drivers of the PLC-500 type is described below:
Allen-Bradley PLC-500 Addressing: Allen-Bradley Driver Tag Properties
|
Allen-Bradley Driver Tag Properties Folder Tab |
Property |
Value |
|
PLC Type |
PLC-500 | |
|
PLC Address |
1 | |
|
Port |
COM1 or COM2 | |
|
Time-out Limit |
1 Note: If you wish your scan interval to be 0.1, you may wish to decrement your Time-out Limit. | |
|
ENQ Delay |
0 | |
|
VTS Station Address |
0 (your base address) | |
|
Retries |
1 | |
|
Hold |
deselected | |
|
BCC |
selected | |
|
Half-Duplex |
selected |
Allen-Bradley PLC-500 Addressing: Serial Port Tag Properties
|
Serial Port Tag Properties Folder Tab |
Property |
Value |
|
Data Bits |
8 | |
|
Stop Bits |
1 | |
|
Baud Rate |
19200 | |
|
Echo |
deselected | |
|
TRS Keying |
deselected | |
|
Key Up Delay |
0.1 |
Note: For a list of all available data type suffixes that can be used for tag I/O addresses, please refer to Data Type Suffixes for Tag I/O Addresses.