Xylem H-3531 FlashLite - Manual (Page 18)

2-6 Installation
H-3531
2.5.2 RS-485 Interface(Industrial Mode Only)
2.5.2.1 Modbus
Modbus is an industry standard serial digital interface for interconnecting Programmable
Logic Controllers (PLCs), intelligent sensors and other devices. The H-3531 FlashLite™
is a Modbus slave and has a serial RS-485 port for connecting to a Modbus compatible
host device. See Appendix B for the Modbus register definitions. Continuous +12Volt
power must be supplied to the H-3531 FlashLite™.
To activate the Modbus interface, the user must issue an extended SDI-12
command/change the power mode to 4 using the simple RS-232 menu interface(see
chapter 4 and 5) and set Power_Mode=4. This setting causes the H-3531 FlashLite™ to
remain awake and monitor the RS-485 port for Modbus messages. This setting can be
made at the factory if requested.
2.5.2.2 H-355 Control
The H-355 Control interface allows the user to program the H-355 Gas Purge System to
meet the environment that it is installed in. This is also an option that the user must enable
by sending the appropriate SDI-12 command or by using the simple RS232 menu interface
as explained in chapter 4 and 5. Once enabled this feature makes setting up the H-3531
FlashLite™ with the H-355 Gas Purge System quick and easy. As shown in Figure 2.1 on
page 2-2.