Xylem H-3553 - Manual (Page 26)

SETUP & OPERATION
24
Modbus Mode Enable
The Modbus mode enable is the setting that determines whether the H-3553 will communicate with a Modbus
master device. Modbus is an industry standard serial digital interface for interconnecting Programmable
Logic Controllers (PLCs), intelligent sensors and other devices. The H-3553 can be used as a Modbus slave
and has a serial RS-485 port for connecting to a Modbus compatible host device. See the “Chapter 5 Modbus
Operation” for more information on Modbus settings Modbus register definitions. Note: this mode requires
more power because it does not go to sleep, the normal operation current draw increase to about 14mA
instead of normal mode of about 6mA.
The H-3553 Modbus mode enable default is 0 meaning disabled/off. To enable the “Modbus Mode” using
the RS-232 main menu, press the ‘P’ key to enter the “Advanced Options” menu and then press the ‘M’ key
to enter the “Modbus Setup” menu. Then press the ‘M’ key in this menu and the Modbus mode enable will
change to on.
To change the H-3553 Modbus mode enable using the SDI-12 interface, send the “aXWME1!” SDI-12 extended
command to enable or change the ‘1’ to a 0 to disable. The response should be “a0021” which means that
it will take 2 seconds to complete the command and then it will put 1 data value in the buffer. To check the
Modbus mode enable and verify it was written correctly send “aXRME!” and wait the responded time. Then
send the “aD0!” command to read back the Modbus mode enable. Note Table 4-19, the ‘a’ is the current SDI-
12 address of the H-3553 and the ‘n’ is the desired Modbus mode enable “1 = On” or “0 = Off”.
H-3553 Combo Bubbler setup menu sDI-12 Interface
P – Advanced Options Command: aXWMEn!
: Response: a0021
advanced Options menu Command: aXRME!
M – Modbus Setup Response: a0021
: Command: aD0!
modbus settings menu Response: a + n
M - Modbus Off/On
Table 4-19: Change the H-3553 Modbus Mode Enable
Auto Mode Enable
The Auto mode enable is the setting that determines whether the H-3553 is put in a unique mode. When
in this mode the H-3553 does not go to sleep but stays awake and based on a user defined measure rate
measures itself and updates all the output s like 4-20mA, RS-232, and the SDI-12 buffer. This mode makes it
possible for the H-3553 to run on its own completely independent of a data logger or master device. Note:
this mode requires more power because it does not go to sleep, the normal operation current draw increase
to about 14mA instead of normal mode of about 6mA.
The H-3553 Auto mode enable default is 0 meaning disabled/off. To enable the “Auto Mode” using the