NOVUS n1500lc - Manual (Page 12)

12
10 SERIAL COMMUNICATION
The indicator can be supplied with an asynchronous RS-485 digital communication interface for
master-slave connection to a host computer (master).
The indicator works as a slave only and all commands are started by the computer which sends a
request to the slave address. The addressed unit processes the command and sends back the
answer.
Broadcast commands (addressed to all indicator units in a multidrop network) are accepted but no
response is generated.
CHARACTERISTICS
- RS-485 compatibility with two-wire bus from the host to up to 31 slaves in a multidrop network
topology.
- Up to 247 units can be addressed by the MODBUS RTU protocol.
- Maximum network distance: 1200 m.
- Time of indicator disconnection: Maximum of 2 ms after the delivery of the last byte.
- Communication signals electrically isolated from the rest of the instrument.
- Baud rate: 1200, 2400, 4800, 9600, 19200, 38400 or 57600 bps.
- Number of data bits: 8, without parity or even parity
- Number of stop bits: 1
- Time to start response transmission: 100 ms maximum delay after acknowledging the command.
- Protocol: MODBUS (RTU)
10.1 RS485 INTERFACE: ELECTRICAL CONNECTION
The RS-485 signals are: D1 = D: Bidirectional data line
D0 = D: Inverted bidirectional data line
C = GND: Optional connection. Improves communication performance for
long cable runs.
COMMUNICATION PARAMETERS CONFIGURATION
Two parameters must be configured for serial use:
bavd: Communication speed. All equipments with the same speed.
Adres: Controller communication address. Each controller must have an exclusive address.