RLE 10K V.2.5.a - Manual (Page 33)

rletech.com SeaHawk 10K User Guide 33
4 Modbus Communication
4.2.2 Function 04: Read Input Registers
To read the SeaHawk 10K input values, the master must send a Read Input Registers request
packet.
The Read Input Registers request packet specifies a start register and the number of registers
to read. The start register is numbered from zero (30001 = zero, 30002 = one, etc).
Read Registers Request Packet Read Registers Response Packet
Slave Address (1 byte) Slave Address (1 byte)
04 (Function code) (1 byte) 04 (Function code) (1 byte)
Start Register (2 bytes) Byte count (1 byte)
# of registers to read (2 bytes) First register (2 bytes)
CRC Checksum (2 bytes) Second register (2 bytes)
…
CRC Checksum (2 bytes)
Table 4.4 Read Input Registers Packet Structure
Register Name Description Units Range
30001 Status Bit level status None 0-65535
30002 Leak Distance Location of leak Ft/Decimeters 0-65535
30003 Units Unit of measure 0=Meters
1=Feet 0-65535
30004 Leak Current Leakage current on cable μA 0-65535
30005 Cable Length Installed cable length Feet/Decimeters 0-65535
30006 Leg1 Res Resistance of cable
A read-only value, this value
is calculated directly from the
installed leak detection cable.
Ohms 0-65535
30007 Leg2 Res Resistance of cable
A read-only value, this value
is calculated directly from the
installed leak detection cable.
Ohms 0-65535
30008 Res/Ft Resistance of cable per foot
This value is set through
register 40008
Milliohms*
*to convert this
value to Ohms,
divide the number
by 1000
0-65535
Table 4.5 Input Registers