Page 375 - Gas Detection Systems Training Manual

Internal Register Address
Holding Register Address
Function Code 06- Preset Unit Register Description (Data bits and Parameter Specifics)
2918 42919
2919 42920
2920 42921
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.
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 Page 35 Of 46 Sensor Electronics Corporation For Version 1.2 and above December 2012 P/N 1580282, Rev. 1, 20121228