Veris Industries LDRA6 USER GUIDE User Manual

Page 24

Appendix A: Modbus Communications

User Guide: LDRA6

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484-6510

A-2.2 Read Input Registers

To read the LDRA6 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).

Table 3: Read Input Registers Packet Structure

Read Registers Request Packet

Read Registers Response Packet

Slave Address (1 byte)

04 (Function code) (1Byte)

04 (Function code) (1 byte)

Start Register *2 bytes)

Byte count (1 byte)

# of register to read (2 bytes)

First register (2 bytes)

Crc Checksum (2 bytes)

Second register (2 bytes)

…

Crc Checksum (2 bytes)

Table 4: Input Registers

Register

Name

Description

Units

Range

30001

Status

Bit Level Status (see Table 5) None

0-65535

30002

Leak Current Zone 1

Leakage current on cable

uAmps

0-65535

30003

Leak Current Zone 2

Leakage current on cable

uAmps

0-65535

30004

Leak Current Zone 3

Leakage current on cable

uAmps

0-65535

30005

Leak Current Zone 4

Leakage current on cable

uAmps

0-65535

30006

Leak Current Zone 5

Leakage current on cable

uAmps

0-65535

30007

Leak Current Zone 6

Leakage current on cable

uAmps

0-65535

30008

Input Selection

Bit Level Status (see Table 6) None

0-65535

30009 Reserved

30010

Version

Firmware version

xx.xx X 100

0-65535

Table 5: Status Flags (Register 30001)

Bit

Read Registers Response Packet

1 = Zone 1: Leak is Detected / Contact Closure Alarm

1 = Zone 2: Leak is Detected / Contact Closure Alarm

1 = Zone 3: Leak is Detected / Contact Closure Alarm

1 = Zone 4: Leak is Detected / Contact Closure Alarm

1 = Zone 5: Leak is Detected / Contact Closure Alarm

1 = Zone 6: Leak is Detected / Contact Closure Alarm

06 0
07 0
08

1 = Zone 1 Cable Break Alarm

1 = Zone 2 Cable Break Alarm

1 = Zone 3 Cable Break Alarm

1 = Zone 4 Cable Break Alarm

1 = Zone 5 Cable Break Alarm

1 = Zone 6 Cable Break Alarm

14 0
15 0