External Modbus device registers can be read into the local registers or written from the local registers. The DXM
Controller, as a Modbus master device or a Modbus slave device, exchanges data using the local registers.
Modbus over Ethernet (Modbus/TCP) uses the local registers as the accessible register data.
4.4.2 Local Registers 851–900 (Data Flash, Non-volatile, 32-bit, Unsigned)
The top 50 local registers are special non-volatile registers. The registers can store constants or calibration type data that
must be maintained when power is turned off.
This register data is stored in a data flash component that has a limited write capability of 100,000 cycles, so these
registers should not be used as common memory registers that change frequently.
4.4.3 Local Registers 1001–1900 (32-bit IEEE Floating Point)
These local registers are paired together to store a 32-bit IEEE floating point format number in big endian format.
Registers 1001 [31:16], 1002 [15:0] store the first floating point value; registers 1003, 1004 store the second floating
point number. There are a total of 500 floating point values; they are addressed as two 16-bit pieces to accommodate the
Modbus protocol.
Use these registers when reading/writing external devices that require Modbus registers in floating point format. Since
Modbus transactions are 16-bits, the protocol requires two registers to form a 32-bit floating point number.
4.4.4 Virtual Registers
The DXM Controller has a small pool of virtual registers that show internal variables of the main processor. Some register
values will be dependent upon the configuration settings of the DXM Controller.
Do not use Read Rules to move Virtual Local Registers data into Local Registers. Use the Action Rule > Register Copy
function to move Virtual Local Registers into Local Registers space (1-850).
Registers
Definition
10001
GPS latitude direction (N, S, E, W)
GPS Coordinate Data if the DXM is configured to read an external GPS unit.
10002
GPS latitude
10003
GPS longitude direction (N, S, E, W)
10004
GPS longitude
10011–10012
Resync timer
Engineering use
10013–10014
Resync timer rollover
Engineering use
10015–10016
Reboot cause (Restart Codes above)
Reboot Type
10017–10018
Watchdog reset count
Counter to track how many resets have been caused by the Watchdog
10021
IO Board Battery Voltage (mV)
DXM Base I/O board battery / solar charger statistics.
Refer to the DXM Instruction Manual for more information.
10022
IO Board Battery Charging Current (mA)
10023
IO Board Incoming Supply (mV)
10024
IO Board On board thermistor ( degrees C)
10025–10026
Http Push SSL Acquires
Statistical counts of connections, disconnections and forced disconnects when
the DXM Controller creates a connection using SSL/TLS (Encrypted
connections)
10027–10028
Http Push SSL Releases
10029–10030
Http Push SSL Forced Releases
10031–10032
Http Push Attempts
Statistical counts of connections, disconnections and forced disconnects when
the DXM controller creates a connection using HTTP non-encrypted
10033–10034
Http Push Successes
10035–10036
Http Push Failures
10037–10038
Http Push Last Status
Last DXM Controller push status
10039–10040
Cellular Strength, BER
Cellular signal strength. Value range: 0–31
0 = –113 dBm or less
1 = –111 dBm
2–30 = –109 dBm through –53 dBm in 2 dBm steps
31 = –51 dBm or greater
99 = not known or not detectable; BER not used
10100
Number of read maps in default
Read Map statistics
10101
Number of read map successes
DXM100-Bx Wireless Controller Instruction Manual
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