XLINK 500/100 Operations & Maintenance Manual page # 175
Input Registers
Input registers return the last measured data from the device. Ideally these values should be
requested on a schedule slightly lagging the measurement schedule on the station. This will
ensure data will follow that found in the log. If the last measured data is not acceptable, a live
reading can be forced by writing to the Force Measurement (1010) holding register. Care must
be taken to allow enough time to pass for taking a measurement before requesting the data.
Since the system works with floating point numbers and Modbus only allows for 16-bit registers,
a multiple register read can be used to access the entire reading. The Modbus master device
should be configured to treat these reads as a single floating point number. For example, if
accessing Last measured via an Xpert, read 1 value of type float starting at register 1. The
complete list of registers and their locations are below.
Modbus
registers
Last Measured
measurement
msw
lsw
M1
1
2
M2
3
4
M3
5
6
M4
7
8
M5
9
10
M6
11
12
M7
13
14
M8
15
16
M9
17
18
M10
19
20
M11
21
22
M12
23
24
M13
25
26
M14
27
28
M15
29
30
M16
31
32
..
M32
63
64
Battery Voltage
901
902
Internal Temp
903
904
M1, M2, .. M32 refer to measurements.
E.g., to read the last measured sensor value for measurement M10, read registers 19 and 20 and
combine the result into a single 32 bit IEEE floating point value.
18.5.
Sutron Function Codes
This section describes the use of the Sutron function code to get files, send files and, get the log
over MODBUS. This only applies when the station is a Modbus slave.
The data portion of a packet carrying the Sutron function code (function code 65, or 0x41)
contains a subcode and associated parameters to define the particular function to perform. The
