Devices With Modbus Pod
Power distribution for Modbus ("M") models is shown in the diagram below. These devices may be powered by:
- An internal industrial-grade, 3.6V/19Ah battery ("B" models)
- An external 12/24VDC power source, through a side power line ("L" models)
- Auxiliary power port, which is compatible with 5V USB power sources
The auxiliary port is meant as a temporary power source: If the internal battery is depleted and no other permanent power source is available, you can bring the device back to life by connecting a standard USB power bank to the auxiliary port using the included cable.
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V+ Line of the Modbus Cable
Additionally, there is the V+ line of the Modbus Cable. The line is bidirectional:
(1) You can power an OSS device from the V+ line, as shown in the diagram below. In this case, V+ acts as a 12/24V power input. This arrangement is equivalent to using the side power input. This is useful when you already have a power source to run the attached Modbus device(s) and wish to use it for the OSS as well.
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(2) If you supply 12/24V power through the side power line ("L" devices), you can power Modbus device(s) from the V+ line, as shown on the diagram below. The side power line's voltage comes out on the V+ wire ( there is a slight drop across the device's internal circuitry). An internal 1A resettable fuse protects against excessive V+ currents and shorts.
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Power Priorities
When several power sources are available, OSS has two power priority levels:
- High priority: 12/24V side power (or V+ power when this line is used as a power input) OR 5V auxiliary power*
- Low priority: 3.6V internal battery power
The above means that the battery power is consumed only when no other power source is available.
* When both the 12/24V side power (or V+ power) and the 5V auxiliary power are applied, the OSS' choice is undetermined. However, this scenario makes little sense in practice, as the 5V auxiliary source is meant for situations when the battery is depleted, and no line power is available.
Boosted Power Output
The Modbus cable also features a 12V/50mA VMOD wire. This power output is connected to an internal power booster circuit (step-up regulator). The regulator's power sources are:
- Internal battery
- Side power line
- V+ line, when used as a power input
- Auxiliary power port
Of the above power sources, using the power booster when running on an internal battery is envisioned to be the most useful: Many Modbus devices require 12V power, and the booster can produce this voltage from the 3.6V battery. Another practical scenario is when the OSS runs on 24V (delivered through the side power line or V+), and the attached Modbus device requires 12V.
Note that the booster delivers up to 50mA of power and can only support relatively low-power Modbus devices. The booster has an internal on/off control line. To conserve battery, the OSS' microprocessor only enables the booster when it is time to communicate with attached Modbus sensors(s).