Sensor Electronics SEC Millenium Series Instruction And Operation Manual page 136

Internal Holding
Register Register
Address Address
2918 42919
2919 42920
2920 42921
The SEC 3120 supports sensor preset holding registers as shown in table 11
previously. To avoid accidentally writing to any of these registers, 4000 hex (16384
decimal) must be added to the register value as a password. Parameter registers low, mid,
and high alarm set points and calibration value must be less than the full scale (range) of
measurement. For example, if the range of measurement is 2000 ppm for Chlorine, then
to set 1200 ppm as the high alarm set point, the value of register 42x06 should be 44B0
hex (17584 decimal).
The normal response is an echo of the query, returned after the register contents
have been preset.
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
Function Code 06- Preset Unit Register Description
(Data bits and Parameter Specifics)
Bit-mapped Diagnostics Force Coils And Toggle LEDs.
Bit 0: Force low relay coil (1 = on, 0 = off)
Bit 1: Force mid relay coil (1 = on, 0 = off)
Bit 2: Force high relay coil (1 = on, 0 = off)
Bit 3: Force fault relay coil (1 = on, 0 = off)
Bit 4: Toggle LEDs red/green ( 1 = on, 0 = off)
Duration of force will be approximately 30 seconds unless
re-written.
4000 Hex must be added as a password to write value.
Modbus Listen Only (00FF engages). No response will be
given and unit will not respond to any commands addresses
to it or broadcast, other than command to restore from
listen only (2920).
4000 Hex must be added as a password to write value.
Modbus Restore From Listen Only (00FF engages).
Response will be given and unit will resume responding to
commands addresses to it or broadcast.
4000 Hex must be added as a password to write value.
Page 35 Of 46
December 2012
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228