ATI Technologies Q46 Series Communications Manual

ATI Q46 Modbus Communications Manual
6
O&M Manual
Rev-D (2/16)
1.4 RS-485 Communication
Modbus data transmission is an RS-485 based communication protocol. The RS485 standard
specifies a two-wire, half-duplex serial data bus for connecting up to 32 devices in parallel, at
distances of up to 4000 feet at transmission rates at or below 100KHz. The RS485 standard
allows the user to configure inexpensive local networks and multi-drop communications links
using a twisted pair cable. A typical RS485 network can operate properly in the presence of
reasonable ground differential voltages, withstand driver contentious situations, and provide
reliable communications in electrically noisy environments with good common mode rejection.
Half-duplex means outgoing messages share the same physical medium with incoming
messages. Only one device may transmit at any given time. During any exchange of data
communication, one device must act as master and one or more devices act as slaves. With no
activity on the bus, the master device sends an addressed query to a slave and then gives up the
bus. All slaves receive the message, but only the addressed slave responds.
Series Q46 Analyzer use a plug-in Modbus circuit board shown in Figure 6 on of this manual.
Wiring connections for the communication bus are shown in that Figure.
Devic
e
2
Devic
e
31
Devic
e
32
4000 Feet
(f<100KHz)
Devic
e
1
Slave
1
Slave
30
Slave
31
Master
Query 30
Slave
1
Slave
30
Slave
31
Master
Response

ATI Technologies Q46 Series Specifications

General

Brand	ATI Technologies
Model	Q46 Series
Category	Measuring Instruments
Language	English