Sentry MODBUS I/O Memory Map
Sentry Controller
MODBUS Memory Map
Detail
1All Registers are MODBUS 16 bit registers
2There are five different ways of using MODBUS registers (see italic reference number in left column for each address)
2.1As an Analog Value: In most cases these values are scaled by multiplying by 10.
2.2As eight packed digital states, packed into one register. In this case the remaining 8 bits are unused.
2.3As a digital state where the register value can only be “0” or “1”.
2.4As a computed value, such as where “0” = no alarm, “1” = low alarm, “2” = high alarm.
2.5Control registers, where the SCADA host can write a value, such as alarm reset to the Sentry, or to set calibration concentration, or alarm set point. Note that these registers are read or write.
3Where a series of registers apply only to sensor number 1, the following sequences for sensors 2, through 8 are only referenced by the first applicable register number.
4Some values can be found in more than one place in different formats. For example when Sensor Number 6 is in high alarm and latched:
• Register 40001:5 is the bit which indicates present alarm condition.
• Register 40007:5 is the bit which indicate a latched condition, regardless of the present sensor reading (until reset)
• Register 40466 is a computed value of “2”
5Registers starting at 40224 provide the raw data read from each of the eight sensors. The following describes the data for sensor 1, the remaining registers through 40463 are for sensors 2 through 8:
40224 | Sensor 1 Input Value - Multiplex 0 | – V0 (Reference value of 0 volts) | 0 - 6553.5 | |
40225 | Sensor 1 Input Value - Multiplex 1 | – Vsignal (Current sensor signal) | 0 - 6553.5 | |
40226 | Sensor 1 Input Value - Multiplex 2 | – CH2 (Auxiliary data by type) | 0 - 6553.5 | |
40227 | Sensor 1 Input Value - Multiplex 3 | – CH3(Auxiliary data by type) | 0 - 6553.5 | |
40228 | Sensor 1 Input Value - Multiplex 4 | – Type | 0 - 6553.5 | |
40229 | Sensor 1 | Input Value - Multiplex 5 – Vin (Channel voltage) | 0 - 6553.5 | |
40230 | Sensor 1 | Input Value - Multiplex 6 | – Calibration Switch Position (0=On) | 0 - 6553.5 |
40231 | Sensor 1 | Input Value - Multiplex 7 | – Vref (Reference value of 2.5 volts) | 0 - 6553.5 |
40232 | Sensor 1 Calibration Due Days |
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To calculate the raw signal voltage (for example), since we know Vref :
V = (Vsignal – V0) / (Vref – V0) * 2.5v
March 4, 2005 | Page: 1 |
