Hanna Instruments HI 504903 - Manual (Page 5)

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1. RS485 serial port red LED.
2. Digital input port red LED.
3. SMS enable green LED.
4. SMS disable red LED.
5. Digital output yellow LED.
6. Cellular signal strength green LED’s.
7. Cellular operating status yellow LED.
MECHANICAL DIMENSIONS
FUNCTIONAL DESCRIPTION
1. Backup battery (rechargeable, sealed lead-acid,
12V / 0.8Ah).
2. On board battery connector.
3. GSM module.
4. LED indicators (see figure on next page).
5. RS232 auxiliary communication port
(for local PC communication only).
6. Terminals not used for this model.
7. Terminals not used for this model.
8. Digital input terminal to acquire external information.
9. Digital input terminal to disable SMS sending.
10. Digital output terminal.
11. RS485 serial communications terminal.
12. Power supply input (12 VDC).
13. Fuse (1 A).
14. Power ON/OFF switch.
Unplug the meter before any electrical connection.