TTDM–NMM and - California Detection Systems

Modbus Technical Reference
Serial Port Logging State
The logging state of the TTDM-NMM serial port is determined by Holding Register 40016.
Holding Address Address Name/description of 16-bit value
Register (decimal) (hex) (4 hexadecimal characters)
40016 15 000F TTDM-NMM Serial Port Log State (numerical code)
The numerical code—a decimal value from 0 to 15—selects the logging mode(s):
0 = host port is passive, only receives and responds to messages (default state, and required for Modbus communications).
1 = log or print events to host port as they occur (useful if connected to a serial printer rather than a Modbus host).
2 = log all SIM communication strings to host port (used for remote diagnostics).
4 = log TTDM-NMM time and date to host port each second.
8 = enables terminal emulation mode, which logs LCD display strings and LED states to host port whenever there is a
change, and accepts remote key commands via the host port.
Note: Combinations can be selected by adding the code values together.
Important: For Modbus communications to work correctly, the serial port logging state must be set to 0 (its factory default).
“Coils”— Global Commands and Module Settings
Modbus Function 01 to Read
Modbus Function 05 to Write
Modbus Function 15 to Block Write
Coil Address Address Name/description of 8-bit value
Location (decimal) (hex) (2 hexadecimal characters)
00001 0 0000 Init Network (write 1 to do function per “SIM Network,” page 20)
00002 1 0001 Update Network (write 1 to do function per “SIM Network,” page 20)
00003 2 0002 Clear Memory (write 1 to do function)
00004 3 0003 Restore Defaults (write 1 to do function)
00005 4 0004 Modbus Mode (0 = ASCII, 1 = RTU; see “SIM Network,” page 20)
00006 5 0005 Auto Reset (1 = Yes, 0 = No; see “Leak Setup,” page 19)
00007 6 0006 Audible Alarm (1 = Yes, 0 = No; see “Leak Setup,” page 19)
00008 7 0007 spare
The first four “coils” make it possible to remotely launch special functions normally executed from the TTDM-NMM keypad. If executing
one of these functions, ensure that the Modbus host application writes a 1 to the coil location only momentarily (i.e., that it
does not repeat the write command). When the TTDM-NMM receives the Write 1 command, the function (e.g., Update Network)
begins to execute, and communications may be temporarily delayed until completion of the task. Since these tasks will
change/update data, associated registers should always be re-read following execution of the task.
Note: These coils always send back the value “0” when read.
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