Connecting Reference Air; Connecting The Transmitter To Amodbus™ Network; Connecting Power - Novatech 1732 Technical Manual

4.14 Connecting Reference Air

For 1234 sensors, no reference air connection is required. For oxygen probes, a 1/4" tube connector on the
transmitter should be connected via a nylon, copper or stainless-steel tube to the 'REF' connector on the
probe.
If two probes are being used, a "T" fitting must be supplied to provide reference air supply to both probes.
4.15 Connecting the Transmitter to a MODBUS™ network
The transmitter can be networked to other transmitters and to a network master. The network uses the
transmitter's RS485 port. Up to 31 transmitters can be connected to the network, and can be interrogated by
the Network Master.
NOTE: Hardware Protocol Selection
The communications port of the 1732 can be configured to communicate on either RS232 or RS485. If the
transmitter is to be used on a MODBUS network, the 1732 transmitter must be set to RS485. For further
details see chapter 7.2.25 Communications Port Options.
NOTE: Terminating Resistor
There is a terminating 100 ohm resistor fitted to the 1730-1 PCB. Link LK3 (TERM), in the bottom left-hand
corner of the PCB, is used to connect the terminating resistor. Link LK3 must be removed on all transmitters
except the transmitter on the end of the network line. If the network line from the transmitters is taken from
the middle of the transmitter network string, a terminating resistor should be enabled with LK3 at each end of
the network line.
The MODBUS protocol of the network is –
Baud Rate
Parity
Stop Bits
RS485
Mode
For more details see Appendix 4, MODBUS™.

4.16 Connecting Power

Before commissioning the probe, sensor or transmitter, read the CAUTION paragraphs at the front of this
manual. The green & yellow EARTH wire MUST be connected to earth.
August 2018
1732 Oxygen Transmitter
19,200
Even
1
2-wire (half duplex)
RTU (binary mode)
Network Master
Network -
Network +
Network Comm
Analyser #1
22 Network -
23 Network +
24 Network Comm
Analyser #2
22 Network -
23 Network +
24 Network Comm
Analyser #31
22 Network -
23 Network +
24 Network Comm
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