NOVUS Controller N120 - Manual (Page 14)

NOVUS AUTOMATION 14/14
ANEXO 2 –SERIAL COMMUNICATION
The controller can be supplied with an asynchronous RS-485 digital
communication interface for master-slave connection to a host
computer (master). The controller works as a slave only and all
commands are started by the computer which sends a request to the
slave address. The addressed unit sends back the requested reply.
Broadcast commands (addressed to all indicator units in a multidrop
network) are accepted but no reply is sent back in this case.
CHARACTERISTICS
• Signals compatible with RS-485 standard. MODBUS (RTU)
Protocol. Two wire connection between 1 master and up to 31
(addressing up to 247 possible) instruments in bus topology. The
communication signals are electrically insulated from the rest of the
device;
• Maximum connection distance: 1000 meters.
• Time of disconnection for the controller: Maximum 2 ms after last
byte.
• Selectable speed; 8 data bits; 1 stop bit; selectable parity (no parity,
pair or odd);
• Time at the beginning of response transmission: maximum 100 ms
after receiving the command.
The RS-485 signals are:
D1 D D + B Bi-directional data line. Terminal 16
D0
D:
D - A Bi-directional inverted data line. Terminal 17
C Optional connection that
improves the performance of the
communication.
Terminal
18
GND
CONFIGURATION OF PARAMETERS FOR SERIAL
COMMUNICATION
Two parameters must be configured for using the serial type:
bavd
: Communication speed.
prty : Parity of the communication.
addr : Communication address for the controller.
REDUCED REGISTERS TABLE FOR SERIAL
COMMUNICATION
COMMUNICATION PROTOCOL
The MOSBUS RTU slave is implemented. All configurable
parameters can be accessed for reading or writing through the
communication port. Broadcast commands are supported as well
(address 0).
The available Modbus commands are:
03 - Read Holding Register 06 - Preset Single Register
05 - Force Single Coil 16 - Preset Multiple Register
HOLDING REGISTERS TABLE
Follows a description of the usual communication registers. For full
documentation download the Registers Table for Serial
Communication in the N120 section of our web site.
Address Parameter Register Description
0000 Active SP Read: Active control SP (main SP, from
ramp and soak or from remote SP).
Write: to main SP.
Range: from spll to spkl.
0001 PV Read: Process Variable.
Write: Not allowed.
Range: Minimum value is the one
configured in spll and the maximum
value is the one configured in spkl.
Decimal point position depends on dppo
value.
In case of temperature reading, the value
read is always multiplied by 10,
independently of dppo value.
0002 MV Read: Output Power in automatic or
manual mode.
Write: Not allowed. See address 28.
Range: 0 to 1000 (0.0 to 100.0 %).