S100 Slave - RS-485
The S100 Slave - RS-485 Module is a certified Rhomb.io Module with two RS-485 transceiver IC that convert UART serial stream to RS-485, a serial communications standard widely used in industry for its simplicity and robustness. Due to the module has two transceivers, you can use two RS-485 buses independently or convert the system in full-duplex, it will depend on the configuration of the assembled resistors.
The next figure shows a 3D view for the S100 Slave - RS-485 Module.
- Data acquisition
- Computer and automation systems
- Performance light control
The S100 Slave - RS-485 Module can be used as an interface between the TTL level UART and the RS422/485 communication bus. The module mounts two low power transceivers (ST485), each one has been designed for bi-directional data communications on multipoint bus transmission line (half-duplex applications), but combining the two tranceivers you can convert it in full-duplex. This combination is made by assembling several 0R0 resistors. The two transceivers provide of node termination resistors than can be remove by open a solder jumper if the module is in the middle of the RS-485 bus. The output differential signals are connected to a 3-pin 3.55mm screw terminal. Also, the CH1 is routed to Diff-A pins of the Rhomb.io connectors and the CH2 to EXT pins.
The S100 Slave - RS-485 Module can use the 3.3V or the VSYS rail. You can choose the voltage shorting the corresponding solder jumper. Make sure this rail is enabled on the motherboard you are going to plug this Module.
The following figure identifies the main components onboard:
The next figure shows the block diagram for the S100 Slave - RS-485 Module:
As a summary, the following table indicates the main features:
|RS-485 (dual) Key Features|
|Two low power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver.|
|2x half-duplex or 1x full-duplex applications|
|Low quiescent current: 300 uA|
|Short-circuit current limited|
|Thermal shutdown circuitry|
|Integrated termination resistor|
|Integrated voltage trnaslator|
|Op. Voltage: 3.3 V to 5 V (transceivers) 1.8 V to 3.3 V (cotrol)|
|Op. Temperature: -40 ºC to +85 ºC|
The following table indicates the available serial interfaces of the Rhomb.io standard used in this Module. This table relates the interfaces of the Rhomb.io standard with the net names of the schematic and with the components to which they are connected.
|Rhomb.io Interface||Schematic Signal||Component||Component Pin|
- UART-A: By assembling R7, R8, R12 and R13 and removing R9 and R10, UART-A lines connect with the second RS-485 transceiver, getting in this way a full-duplex system.
All user interface signals pass through a level-shifter in order to guarantee communication between Core/Master Module and the Slave Module even when both work with different logic levels.
GPIOs and Control Signals
The following table summarizes the GPIOs and Control Signals used on the S100 Slave - RS-485 Module. This table relates the signals of the Rhomb.io standard with the net names of the schematic and with the components to which they are connected.
|Rhomb.io Signal||Schematic Signal||Component||Component Pin|
|1WIRE||1WIRE||ID Memory (U4)||IO|
|IO||IO0 (CTRL_1)||ST485 (U2)||#RE|
|IO2 (CTRL_3)||ST485 (U3)||#RE|
- 1WIRE: This signal can be used to read the ID Memory.
- DIFF_N & DIFF_P: Channel 1 RS-485 differential signal are connected to both the Rhomb.io connectors and the screw terminal.
- EXT1 & EXT3: Channel 2 RS-485 differential signal are connected to both the Rhomb.io connectors and the screw terminal. By assembling R3 and R4 resistors you can connect these signals to EXT0 a and EXT 2 respectively.
- IO0-3: These signals enable the receiver and driver outputs of the transceivers. You can short-circuit them by assembling R5 and R6 resistors. Below are the driver and receiver true tables of the transceiver:
Truth table (driver)
Note: X = Don't care; Z = High impedance
Truth table (receiver)
Note: X = Don't care; Z = High impedance
All GPIO and control signals pass through a level-shifter in order to guarantee communication between Core/Master Module and the Slave Module even when both work with different logic levels.
The S100 Slave - RS-485 can use the 3.3 V rail or the VSYS rail. You can choose the voltage shorting the corresponding solder jumper. Make sure this rail is enabled on the motherboard you are going to plug this Module.
You can find more information about power consumption in the ST485 datasheet.
Bill of materials
- Precaution against Electrostatic Discharge. When handling Rhomb.io products, ensure that the environment is protected against static electricity. Follow the next recommendations:
- The users should wear anti-static clothing and use earth band when manipulating the device.
- All objects that come in direct contact with devices should be made of materials that do not produce static electricity that would cause damage.
- Equipment and work table must be earthed.
- Ionizer is recommended to remove electron charge.
- Contamination. Be sure to use semiconductor products in the environment that may not be exposed to dust or dirt adhesion.
- Temperature/Humidity. Semiconductor devices are sensitive to environment temperature and humidity. High temperature or humidity may deteriorate semiconductor devices characteristics. Therefore avoid storage or usage in such conditions.
- Mechanical Shock. Care should be exercised not to apply excessive mechanical shock or force on the connectors and semiconductors devices.
- Chemical. Do not expose semiconductor device to chemical because reaction to chemical may cause deterioration of device characteristics.
- Light Protection. In case of non-EMC (Epoxy Molding Compound) package, do not expose semiconductor IC to strong light. It may cause devices malfunction. Some special products which utilize the light or have security function are excepted from this specification.
- Radioactive, Cosmic and X-ray. Semiconductor devices can be influenced by radioactive, cosmic ray or X-ray. Radioactive, cosmic and X-ray may cause soft error during device operation. Therefore semiconductor devices must be shielded under environment that may be exposed to radioactive, cosmic ray or X-ray.
- EMS (Electromagnetic Susceptibility). Note that semiconductor devices characteristics may be affected by strong electromagnetic waves or magnetic field during operation.
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