GE Industrial Solutions MX350 Communications Guide - Manual (Page 17)

COMMUNICATIONS GUIDE RS485 INTERFACE (MODBUS RTU)
MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – COMMUNICATIONS GUIDE 13
Using the User
Definable Memory
Map
The MX350 contains a User Definable area in the memory map. This area allows re-
mapping of the addresses of any Actual Values or Setpoints registers. The User Definable
area has two sections:
1.
A Register Index area (memory map addresses 020BH-0287H) that contains 125
Actual Values or Setpoints register addresses.
2. A Register area (memory map addresses 020BH-0287H) that contains the data at the
addresses in the Register Index.
Register data that is separated in the rest of the memory map may be re-mapped to
adjacent register addresses in the User Definable Registers area. This is accomplished by
writing to register addresses in the User Definable Register Index area. This allows for
improved throughput of data and can eliminate the need for multiple read command
sequences. The User Definable Register Index is stored as a setpoint and therefore it is
“remembered” even when the power is removed.
For example, if the values of ATS STATUS (register address 013FH; modbus address 30320)
and EXERCISER STATUS (register address 0838H; modbus address 32105) are required to be
read from a MX350, their addresses may be re-mapped as follows:
1.
Write 30320 to address 020BH (40524) (User Definable Register Index 0000) using
function code 06 or 16.
2. Write 32105 to address 020CH (40525) (User Definable Register Index 0001) using
function code 06 or 16.
The MX350PC software can be used to write these locations to the User Definable Register
Index using the Setpoints > Modbus Memory Map > User Map screen.
It is now possible to read these two data registers with one read, at addresses 020BH,
020CH. Address 020BH will contain ATS STATUS. Address 020CH will contain EXERCISER
STATUS.