ABUS Technologies Field Logger Data Acquisition/Recorder - Manual (Page 13)

ABUS TECHNOLOGIES INC.
13
Field
Logger
take a look at it after applying a new configuration to the Field Logger. Click on the Apply button to send
the new configuration. The OK button will also transmit the new configuration to the Field Logger,
closing the window. The Cancel button simply closes the window, discarding any changes.
7.5 Serial Communication
The Field Logger communicates with the Configurator or the application software by its RS485
serial interface, using the Modbus protocol. The computer is the master and the Field Logger is the
slave. The communication is always started at the host (master), which transmits a command to the
destination address. The addressed slave (a Field Logger) recognizes the request and answers back to
the host. The Field Logger also responds to broadcast type commands.
OBS.: It is recommended to use a 326AWG shielded cable for serial communication.
7.5.1 Characteristics
 RS485 standard (2 wire, isolated)
 Address capability for 247 instruments in the same network (31 instruments maximum per
segment)
 Distance: 1000m (4000 feet)
 Baud rates: 1200, 2400, 4800, 9600 or 19200 bps.
 No. of bits : 8, no parity
 Stop bits: 1
 Response delay: 20ms max.
 Protocol: MODBUS (RTU)
7.5.2 Registers
The Field Logger configuration parameters are organized in a table of registers. Using the block
read capability of the protocol; many registers can be viewed in a single request command.
The user does not need to know the parameter position in the table as long as he uses the
Configurator software. A parameter is a word of 16 bits. The MODBUS command used for reading is:
03 - Read Holding Register
The following registers are equivalent to the holding registers (4X reference):
Holding
Registers
Parameter
0001 Channel 1 current reading
0002 Channel 2 current reading
0003 Channel 3 current reading
0004 Channel 4 current reading
0005 Channel 5 current reading
0006 Channel 6 current reading
0007 Channel 7 current reading
0008 Channel 8 current reading
0009 Alarm status
0010 Reserved: general status
0011 Channels 1 and 2 status
0012 Channels 3 and 4 status
0013 Channels 5 and 6 status
0014 Channels 7 and 8 status