If the 'standard' Duty/Standby functionality of the RTD-10 does not meet your requirements, e.g. you need Duty/Standby rotation for Heat and Cool, then custom solutions need to be implemented on your BMS.
Examples:
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Q: Can I use the a BMS Master to control the RTD-10 interfaces as if in Duty/Standby Mode?
A: Yes. You can operate the RTD-10 in Standard mode and control them via your BMS system via hardwired inputs (S1 - S6) and/or Modbus such that they operate as if in Duty/Standby.
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Q: I have two RTD-10 interfaces and want one to run in Cool mode while the other runs in Dry mode. Is it possible to program the RTD-10 interfaces such that they rotate between these two mode and the master RTD-10 tells the other to run in the other mode?
A: This is not possible. You will have to use your BMS system to control the RTD-10 modes.
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Q: I need the Daikin units to operate on Duty/Standby to maintain a set-point of 21 DegC. Is this achievable? I can go either modbus (read/write) or provide resistances to switch between the modes.
A: The RTD-10 Duty/Standby function is not designed for Duty/Standby in close control applications requiring heating and cooling and cannot be modified to support this.
To implement this you will require an external PLC/BMS to implement the Duty/Standby with duty rotation. This can be achieved by using two RTD-10s in standard resistance mode, or alternatively two RTD-NETS if you are using Modbus (you can also use RTD-10 for Modbus control). By using the AUTO mode you can avoid the need for heat/cool changeover. You can detect fault conditions either from the VFC relay output of the RTD-10 or from the Modbus Group IsFault register. If using Modbus you can also monitor the unit or group return air temperature and bring On the standby unit if room temperature diverges more than a specified amount from the setpoint.
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Q: Duty/Standby prohibits Auto mode of the Daikin equipment. However, our application requires to run in auto mode.
A: An option to run in auto mode would be to manually configure RTD #1 in run and RTD # 2 in standby in standard resistance mode by using the fault output of RTD #1 to activate RTD #2, however you would require additional external hardware to achieve rotation and temperature alarm operation.
A hardwired duty/standby solution would consist of a timer relay for changeover with RTD fault relays used to switch both zones on, together with a high temperature thermostat that activates both RTDs if temperature exceeds a certain limit.If you are using BMS then you can implement the complete control functionality using the BMS control strategy. Configure the RTD-10s for Resistance Mode (DIP 1-4 off), address them as Modbus addresses 1 and 2, then use the RTD Modbus Registers documented in the RTD-NET datasheet on our website to switch the units on and off, set the setpoint and mode, and readback fault and temperature data.
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Q: Can I have only two RTD-10 interfaces in Duty/Standby Mode and then have a third RTD-10 switch on only if power is lost on any of the two Duty/Standby units?
A: This is not possible, because the third RTD-10 is not part of the Duty/Standby network. A workaround could be an external relay that closes the power circuit of the third RTD-10 when any of the first two indoor units loses power.
Another option is to operate all RTD-10 interfaces in Standard operation mode and set the application algorithm through your BMS system. The BMS system can control the indoor units via hardwired connections or via Modbus and would have to emulate the Duty/Standby mode (if wished).