When Atlas-Copco installs the gateway they should have given you a document with the specific registers of that gateway. If you had a copy if the software used to configure the gateway you could do it yourself.
To quote an old email i dug up from an Atlas Copco service technician "Also attached is the rather exhaustive address list for a Mk4 elektronikon controller as it applies to the Mk4 controller. In the attempt to cover every variation... the guide covers different types of equipment and their nuances along with the standard registers. In particular Sections 2.3.2; 2.3.3; & 2.5.1.2 may be of particular interest.
The detailed address report would look something like this:
AC MkIV reporting file
Monday, March 02, 2015
Modbus IO definition
Analogue Inputs
===============
Compressor Outlet
Pressure - mBar
Status : reg 1, Value : reg 2
Dp Air Filter
Pressure - mBar
Status : reg 3, Value : reg 4
Oil Pressure
Pressure - mBar
Status : reg 5, Value : reg 6
Intercooler
Pressure - mBar
Status : reg 7, Value : reg 8
Element 1 Outlet
Temperature - 0.1°C
Status : reg 9, Value : reg 10
Element 2 Inlet
Temperature - 0.1°C
Status : reg 11, Value : reg 12
Element 2 Outlet
Temperature - 0.1°C
Status : reg 13, Value : reg 14
Compressor Outlet
Temperature - 0.1°C
Status : reg 15, Value : reg 16
Oil Temperature
Temperature - 0.1°C
Status : reg 17, Value : reg 18
Cooling Water In
Temperature - 0.1°C
Status : reg 25, Value : reg 26
Cooling Water Out
Temperature - 0.1°C
Status : reg 27, Value : reg 28
Digital Inputs
==============
Emergency Stop
Status : reg 201, Value : reg 202
Remote Start/Stop
Status : reg 203, Value : reg 204
Remote Load/Unload
Status : reg 205, Value : reg 206
PB1 open / PB2 closed
Status : reg 207, Value : reg 208
Overload Motor
Status : reg 209, Value : reg 210
Starter Feedback Contact
Status : reg 213, Value : reg 214
Electr. Condensate Drain
Status : reg 217, Value : reg 218
Counters
========
Running Hours
Value : reg 301 + 302
Loaded Hours
Value : reg 303 + 304
Motor Starts
Value : reg 305 + 306
Module Hours
Value : reg 307 + 308
Load Relay
Value : reg 311 + 312
Special Protections
===================