How does DAE's Modbus compare with Advantech and others?
(1) Combination I/O. DAE uses combines different types of I/O onto a single module. Whereas Advantech and others have discrete I/O modules, i.e. DI only, DO only or AI only. Thus when an application requires a combination of measurement, control and monitoring functions, one needs only one module from DAE but may require multiple modules from Advantech and others. Not only is the capital cost much less, but the installation labor cost is likewise greatly lessened as result.
(2) The Modbus protocol is the standard for DAE's I/O modules, whereas for Advantech and others it is available as a separate model at a higher premium compared to their regular modules using their own proprietary protocol.
(3) Internal relay. For most facility automation, the devices controlled must be done through a relay, a simple DO (open collector)
will not suffice. The DO for all of DAE's modules come with the relay already built into each DO. Whereas for Advantech and others, DO with relays are not included as standard, their DO must be matched with an external relay or they only have an A type terminal (Form A, 0.25 A low current), they do not have a C type terminal, only the model 4096 supports an 8 channel power relay (4 sets of C type + 4 sets of A type) and does not even include DI on the same module. For control applications using DO, DI is more often than not also required as a means of obtaining feedback, so not including DI on the same module with a DO would incur extra equipment cost.
(4) DAE's I/O modules have noise immunity built in from the get-go, Advantech and others have this as feature only for the Robustic version which comes in only 4 variations, meaning that their other models are ordinary and not designed for such.
(5) With a variety of models offering differing combinations of I/O, more often than not one can find just the right module that is exactly needed instead of having to buy multiple modules when one will do.
What is so unique about the robustness of DAE's I/O modules?
DAE's I/O modules have designed with noise immunity in mind right from the start. Which can withstand up to 4 kV during an EFT test, compared to Advantech's highest grade Robustic models which can only achieve 3 kV. Because DAE's modules have been designed for the power monitoring market, these modules can be installed together with the high or low power circuits within the same panel enclosure, there is no need to provide a separate panel and shielding just for the I/O modules. Besides the harsh noise environment that exists within the panel, the temperature is also quite high to which DAE's modules is also designed to withstand.
Why install the modules together with the high/low voltage panels, and not provide a separate dedicated panel?
From the point of view of installation labor costs and capital costs, providing a separate dedicated panel just for the modules would greatly increase the overall cost. This is because the majority of the points being monitored would be within the same panel, thus, when a separate panel is used, all the points need to be wired out of the panel into the separate panel with its accompanying need for extra planning, coordination, implementation, as well extra materials needed to carry out the task, and additional labor. In addition during testing phase, there is the need to have at least two people be at each of the panel location to coordinate the test. Clearly the overall cost and complexity of having a separate panel greatly exceeds having the module be placed within the same panel.
Why are DAE's modules suited for installation in same panel as the power equipment, while other brands are not?
In order to meet this requirement, the product must be:
(1) The noise immunity must be very high
(2) The equipment must tolerate high temperatures
(3) It must occupy little space, for which combination I/O is aptly suited, and the relay must be included with the DO, so no extra space is needed. Otherwise the space needed for all the modules and extra devices would exceed the space available within the panel.
What are the advantages of having the built in relay for each DO?
The majority of DO is used for load control, which can be only be one of two types:
(1) For most three phase magnetic contactor, the control voltage needs to be 220 Vac. Thus if the DO cannot accept 220 Vac, then an external intermediate relay must be added, which will also engender the need for another power source, all of which increases the capital as well as labor costs.
(2)Single phase 20A AC load, the LT3504 is recommended for this type of application. As the LT3504 can be used accept a 20A load directly, not only is an intermediate relay not needed, but the magnetic contactor for the load is obviated as well.
Of course from the point of view of a facility monitoring application, there is no such thing as a DO controlled point without accompanying DI for feedback. It bears to mention then that an Advantech based solution would require an additional DI module, which would mean two modules is needed to do the work of one module from DAE.
What are the unique features of the relay output control?
Most output control are simple on/off control, but DAE's relay output control can operate in three different modes depending on the type of application which greatly simplifies the central host software and increase system reliability.
(1) Simple mode: simple on/off control, the relay return to its normal status after the power is restored from an interruption.
(2) Retain mode: similar to simple mode, except that the relay will automatically be restored to the last status before the power interruption has occurred. With this feature, there is no need to explicitly send a command from the central host after the power is restored.
(3) Pulse mode: sends a short pulse to the controlled point, most often used for ACB/VCB control applications.
Besides the more common AI/DI/DO, what other special models are available?
DAE specializes in the area of facility monitoring, thus there are other models which perform specialized functions.
The LT3504 supports up to 4 loads, each up to 20A. It comes with Modbus communication and on board manual switch.
The SIO235C provides on board temperature sensors, suitable for measuring water or air temperature.
The IS70 with built-in temperature sensor and 2 DI and 1 relay.
Can the same power supply be used for both the working power and the relay control?
This is a very disastrous way of doing things. Fortunately however, DAE's modules aside from needing a power supply for the working power of the module, does not require any other power supplies. As compared with typical I/O modules that need another set of power supply for the DI, and yet another set for the DO.
The reason that the power supply needs to be separate is because the main module, the DI and the DO must all be isolated from each other, otherwise they will interfere with each other. In addition to the optical isolation provided for each DI, DAE's modules are also equipped on board with a DC to DC converter that supplies the power for the I/O and provides additional isolation at the same time.
Why can't a single 24V DC source be shared?
It so happens that in order to reduce costs, a single power supply (such as 24V DC) is used as the working voltage, and also provide the power for the DI and DO. Although expedient, doing so would cause all three to have a single common and thus any noise from the DO will affect the CPU operations, the same with the DI. It can also happen that the noise from the DI will cause the DO to operate erratically and cause sporadic errors which would be near impossible to troubleshoot.