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4
DATALOGGER
NI2400
MODBUS TCP (SCADA INTEGRATION)
Overview
Modbus ADU (application data unit) is sent in form of TCP packets. All Modbus TCP ADU
are sent via TCP to registered port 502.
Modbus over TCP allows NI2400 integration in LabVIEW and SCADA systems. By reading
holding registers, it's possible to gather all sensors data (analog, smartmodbus, multiplex-
ers, digital inputs), events and alarm, datalogger status and information.
• It's possible to read sensor's alarm status.
• By integrating NI2400 in a SCADA, industrial plant remote monitoring and logging are
possible without the need on-site visits.
• Maintenance costs are reduced through centralized control and monitoring to minimize
downtime.
• Centralized alarms to improve operational effectiveness.
• Data could be available in mobility (depending on used SCADA).
COMMUNICATION
Communication Bus
Communication bus for this module is Ethernet interface.
Port used for TCP communication is 502 (Modbus TCP Standard Port)
Modbus function to use for registry reading is ReadHoldingRegister.
Measure Register
For each sensor (analogs, digitals, multiplexers and virtual channels), 16 registers will be
exported. Input A's last acquired measure (Offset 0-1), input b (Offset 2-3), sensor's tem-
perature (Offset 4-5), Acquisition's timestamp (Offset 6-7-8-9-10-11-12-13-14) and different
flags to show acquisition status and alarm status (Offset 15).
Measures will be communicated in float IEEE754 standard.
Endialess can be user configured by writing 0-1-2-3 values into configuration register at
0x5000 address.
Following table will represent 4 endianless configurations:
IEEE754 = AA:BB:CC:DD
AA = MSB
DD = LSB
Configuration=0 (default)
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4
DATALOGGER
NI2400
AA
MSB Modbus address 0 LSB Modbus address 0 MSB Modbus address 1
Configuration=1
BB
MSB Modbus address 0
Configuration=2
CC
MSB Modbus address 0
Configuration=3
DD
MSB Modbus address 0
Timestamp details
Timestamp is composed by 9 registers, with offset 6 (MSB) to 15 (LSB). Timestamp is an
ASCII string 18 bytes long, in the following format: "dd/mm/yy hh:mm:ss"
Flag's Register
Flag's register is mapped as it follows:
BIT
0 Sensor acquired
1
2
3 Valid Temp input
4
5
6 Temp alarm Input
090
BB CC
AA DD
LSB Modbus address 0 MSB Modbus address 1
DD BB
LSB Modbus address 0 MSB Modbus address 1
CC AA
LSB Modbus address 0 MSB Modbus address 1
CONTENT
A valid Input
B valid Input
A alarm Input
B alarm Input
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DD
LSB Modbus address 1
CC
LSB Modbus address 1
AA
LSB Modbus address 1
BB
LSB Modbus address 1
091