NTI ENTERPRISE ENVIRONMENT MONITORING SYSTEM
100
Mapping (Cont’d):
Input # (Address) ENVIROMUX-16D ENVIROMUX-5D ENVIROMUX-2D
8 Remote DI #1.1 Remote DI #1.1 Remote DI #1.1
… ... ... ...
23 Remote DI #1.16 Remote DI # 1.16 Remote DI #1.16
24 Remote DI #2.1 Remote DI #2.1 Remote DI #2.1
… ... ... ...
39 Remote DI #2.16 Remote DI #2.16 Remote DI #2.16
… … … N/A
8 + (M – 1) * 16 + N - 1 Remote DI #M.N Remote DI #M.N N/A
… … … N/A
72 Remote DI #5.1 Remote DI #5.1 N/A
… … … N/A
87 Remote DI #5.16 Remote DI #5.16 N/A
248 Remote DI #16.1 N/A N/A
N/A N/A
263 Remote DI #16.16 N/A N/A
Function Code 04 - Read Internal/External Sensors floating point values
Floating Point Format
The values of analog sensors are in floating point format. For this reason, two 16-bit registers are used to represent the value of
each sensor. The format is IEEE 32-bit Floating Point Big Endian with byte-swapped (the order of bytes is 3,4,1,2)
Description:
Function code 04 is used to read the values of Internal Sensors and External Sensors. If external sensors are of a contact type, a
value of 0.0 will represent a closed contact and a value of 1.0 will represent an open contact. Two consecutive 16-bit registers are
used for each sensor.
Query:
Slave
Address
Function
Code
Starting
Address High
Starting
Address Low
Quantity of
Inputs High
Quantity of
Inputs Low
CRC CRC
Note: because two registers are needed to represent any sensor in Input Registers, the Quantity of Inputs value should be the
double of the number of sensor to read.
Response:
The sensors value in response messages are packed as IEEE 32-bit Floating Point Big Endian format and they use 4 bytes for
each value. The Modbus protocol has a single byte count which represents the number of 16 bits register. Because of this, the
protocol can process up to maximum 64 floating point values in a single request.
Slave
Address
Function
Code
Byte Count Data Data …. CRC CRC
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