9
Modbus Register Map
Register Values
Little Endian Ordering
All 32-bit values are stored such that the least significant bits are in the lower of the 2 register addresses (a.k.a. Little
Endian). For example, Tank 1 Product level is stored in registers 204 and 205. If the value happened to be large enough
that it spanned 2 registers, say 9876.5 gallons, the values would be stored as follows:
Gallons resolution is 0.1, so the floating point value is multiplied by 10 and converted to the integer value 98765. In hex,
this value is 0x000181CD. Mapping this into registers:
Address 204: 0x81CD
Address 205: 0x0001
Two’s Complement Integer Representation
Negative values are stored as 2’s complement values. So, for the sake of a simple example let’s say we had -9876.5
gallons. The 2’s complement value of -98765 in hex is 0xFFFE7E33. By noting the highest bit is a 1, you know the
number is signed. To get the positive value you simply invert the bits and add 1, getting you back to 0x000181CD. This will
be set up in the Modbus client software.
The following is a table of Input Register addresses that can be accessed using function code 0x04.
Register Mapping Overview
Register Addresses
Data Set
Data Type
100-107
System Units
System Unit Setting
200-235
Tank 1
Tank 1 Data
236-271
Tank 2
Tank 2 Data
272- ….
Tank 3 …
Tank 3 Data …
2756-2791
Tank 72
Tank 72 Data
2792-3199
Reserved
3200-3225
Manifold 1
Manifold 1 Data
3226-3251
Manifold 2
Manifold 2 Data
3252-….
Manifold 3…
Manifold 3 Data…
4110-4135
Manifold 36
Manifold 36 Data
4136-4499
Reserved
Reserved
4500-4501
2-Wire Sensor 1
2-Wire Sensor 1 Data
4502-4503
2-Wire Sensor 2
2-Wire Sensor 2 Data
4504-….
2-Wire Sensor 3…
2-Wire Sensor 3 Data …
4642-4643
2-Wire Sensor 72
2-Wire Sensor 72 Data
4644-4799
Reserved
Reserved
4800-4802
3-Wire Sensor 1
3-Wire Sensor 1 Data
4803-4805
3-Wire Sensor 2
3-Wire Sensor 2 Data
4804-….
3-Wire Sensor 3...
3-Wire Sensor 3 Data …
4941-4943
3-Wire Sensor 48
3-Wire Sensor 48 Data
4944-4999
Reserved
Reserved
5200-5206
Mag Sensor 1
Mag Sensor 1 Data
5207-5213
Mag Sensor 2
Mag Sensor 2 Data
5214-….
Mag Sensor 3…
Mag Sensor 3 Data
5697-5703
Mag Sensor 72
Mag Sensor 72
5704-5899
Reserved
Reserved
5900-5901
PS Relay 1
PS Relay 1 Status
5902-5903
PS Relay 2
PS Relay 2 Status
5904-5999
Reserved
Reserved
Summary of Contents for INCON TS-550evo
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