RKI Instruments Digester Gas Monitor - Manual (Page 78)

72 • Supported Modbus Functions Digester Gas Monitor Operator’s Manual
NOTE: All Digester Gas Monitors on a Modbus network must be configured with the
same baud rate and parity, and each Digester Gas Monitor must have a unique
slave ID. For a Digester Gas Monitor to participate on a network, the ENABLED/
DISABLED setting must be set to ENABLED.
Supported Modbus Functions
The Digester Gas Monitor supports Function Code 03, Read Holding Registers. There are
a total of 57 registers available to be read via this Function Code.
Register 40001, Instrument Information
The format for the first register, register 40001, is shown below in Table 13. Register
40001 gives information about the instrument as a whole, and should be checked before
reading or interpreting the channel data in the registers that follow. When the Digester Gas
Monitor is in any operating menu or mode other than normal operation, the channel
registers simply hold their existing values. Once the Digester Gas Monitor returns to
normal operation, the channel registers are updated each second.
Response Delay The response delay can be set from 0 (factory setting) to 20 mS.
This is an optional additional delay inserted by the Digester Gas
Monitor prior to returning a response message to the Master. It
may be helpful in some installations where the Master’s
preparedness to receive responses might be delayed.
Table 13: Register 40001
Current Operating Mode
(MS-Byte)
Common Resource Status Bits
“1” = Energized “0” = De-Energized
(LS-Byte)
• 0 = Normal Operation
• 1 = Factory (Reserved)
• 2 = Input Setup Menu
• 3 = Channel Configuration Menu
• 4 = Global Menu
• 5 = Modbus Menu
• 6 = Calibration Mode
• 7 = Min/Max Display
• 8 = Low Power Standby
• Bit-7 (msb) = Common Fail Relay
• Bit-6 = Relay-A
• Bit-5 = Relay-B
• Bit-4 = Relay-C
• Bit-3 = Relay-D
• Bit-2 = Strobe (optional)
• Bit-1 = Audible Alarm (Buzzer)
• Bit-0 (lsb) = Flow Fail
Table 12: Modbus Configuration Parameters (Continued)
Modbus Mode Parameter Available Settings & Description