Absolute notation item names
- Last UpdatedAug 29, 2024
- 1 minute read
The MBTCP Communication Driver also uses another naming convention called the Absolute Notation. This naming convention is independent of the PLC model numbers.
The Absolute naming convention allows access to the four Modbus data types, each with an address from 0 to 65535. The data types are indicated by the item name suffix characters.
|
Item Name |
Description |
Range |
|---|---|---|
|
nnnnn DO |
Discrete Output Refers to the same data Modbus calls "coils." |
0 (zero) DO through 65535 DO |
|
nnnnn DI |
Discrete Input Refers to the same data called "contacts" by Modbus. |
0 (zero) DI through 65535 DI |
|
nnnnn IR |
Input Register Refers to the same data called "input register." |
(zero) IR through 65535 IR |
|
nnnnn HR |
Holding Register Refers to the same data Modbus calls "holding register." |
0 (zero) HR through 65535 HR |
|
nnnnn PV |
Process Variable Refers to holding register, but treated as floating points and assumes two (2) registers per floating-point number. |
0 (zero) PV through 65535 PV |
The IR and HR absolute notation can also be combined with the following conversions: L (long), F (floating), S (signed), or U (unsigned).
For example:
-
219 HRS 16-bit signed integer
-
000 HRL 32-bit signed integer
-
100 HRF 32-bit floating point
-
000 HRU 32-bit unsigned integer
-
100 HRLF 64-bit floating point
-
000 HRLL 64-bit signed integer
-
000 HRUL 64-bit unsigned integer