EZT-570S User Manual
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9.1 Serial
Communications
The EZT-570S uses Modbus RTU protocol for serial communications. The EZT-570S communication
address and parity can be changed on the User communications screen located under the system
settings menu.
Figure 9-2 Modbus Settings
The EZT-570S is set by default for an address of 1 and even parity for use with CSZ’s EZ-
View software package. If another software package is being used, or you are writing your
own custom application, see the EZT-570S User Communications Reference Manual for
instructions and information on command structure and protocol usage.
9.1.1
Adjusting Modbus Serial Communication Settings
The Modbus serial communication settings allow the EZT-570S to be used on a single (RS232) or
multi-drop (RS485) serial link. The settings must be set to match that of the host computer and vice
versa. The serial port settings of the EZT-570S are fixed other than the controller address and parity.
The host computer’s serial port must be set to match the fixed EZT-570S port settings:
Address:
1-31 (user selectable)
Baud Rate: 9600
Data Bits: 8
Stop Bits: 1
Parity:
none, odd, even (user selectable)
The
Modbus Address
is used to identify the EZT-570S on the serial link. When a multi-drop
connection is used, each controller on the link must have a different address so that each one can be
identified separately. If two or more devices have duplicate addresses, communications with those
devices will fail because they will all try to respond to the same message. For single controller
connections, the address only needs to match that of the commands being sent from the host
computer.
The
Parity
setting is an extra level of error checking that the serial ports of devices can use to verify
that the data received is what was sent. All devices on the serial link must be set to the same parity
setting or they will not transmit and receive data the same way. Thus, communications will fail
between devices that do not have the same settings.
Summary of Contents for EZT-570S
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