SPECIFICATIONS

The TTL to RS485 module can realize the mutual conversion between TTL level and RS485, use differential signal to transmit data, half-duplex communication, the dip switch on the module controls whether to connect the 120Ω resistor, supports long-distance transmission and multi-point communication, and has functions such as failure safety, current limiting protection, and overvoltage protection.

Parameter characteristics:

◆ Transceiver: SIT3088E

◆ Communication mode: half-duplex communication

◆ Signal transmission mode: differential transmission

◆ Bus fault tolerance voltage range: ±15V

◆ Working voltage range: 3.0V~5.5V

◆ Working temperature range: -40℃-125℃

◆ Data transmission rate: up to 14Mbps

◆ Transmission distance: maximum about 1219 meters (depending on the quality of the transmission line and the baud rate)

◆ Load capacity: 1/8 unit load, allowing up to 256 devices to be connected to the bus

◆ Characteristic impedance: 120Ω (Dip switch control, default closed, dip ON ◆ Bus port electrostatic discharge (ESD) protection capability: up to 15kV or more under human body discharge model (HBM)

Note: In actual application, the data transmission rate is affected by multiple factors such as transmission line quality, transmission distance and the maximum baud rate supported by the main control serial port.

(It is recommended to open the module schematic and look at the real object at the same time)

There is an LED power light on the module, which is always on after power-on

D1 is a Schottky diode, which has a reverse isolation function to prevent voltage from affecting 3V3

SW1 is a dip switch, which controls whether the 120Ω resistor is connected to the end of the RS485 line. It is closed by default and can be closed for short-distance communication. For long-distance communication, you can choose to open one or both at the same time, depending on the actual situation

DN1 is a TVS diode, which is used to protect the RS485 interface from the influence of transient voltage caused by electrostatic discharge (ESD), electrical fast transients (EFT) and lightning

U1 SIT3088E transceiver

VCC: Connect to the power supply, the silk screen is 3V3, and can be connected to 3.0V~5.5V

GND: Ground

DE: Driver output enable control, high level is valid, and the output is high impedance when low level

DI: DI driver input, when DE is high level, the low level on DI makes the driver in-phase terminal A The output is low level, and the driver's inverting terminal B output is high level; the high level on DI will make the in-phase terminal A output high level and the inverting terminal B output low level

/RE: Receiver output enable control, when low level, the receiver output is enabled, RO output is valid, when high level, the receiver output is disabled, RO is high impedance

RO: RO receiver output, when /RE is low level, if A-B≥-10mV, RO output is high level; A-B≤-200mV, RO output is low level

A: Receiver in-phase input and driver in-phase output, connected to the A end of the RS485 bus

B: Receiver inverting input and driver inverting output, connected to the B end of the RS485 bus

The lead-out pin TXD, that is, the DI of the transceiver corresponds to the TXD of the master control, RXD, that is, the RO of the transceiver corresponds to the RXD of the master control, DIR is high

level to send data, DIR When the level is low, it is receiving data, and the module does not have a low power shutdown mode.

The CAN transceiver module can realize the conversion between TTL level and CAN, use differential signal to transmit data, half-duplex communication, the dip switch on the module controls whether to connect to the 120Ω resistor, supports multi-point mutual communication, and has short circuit protection, over-temperature protection, under-voltage protection and other functions

Parameter characteristics:

◆ Transceiver: SIT1042AQT/3

◆ Communication mode: half-duplex communication

◆ Signal transmission mode: differential transmission

◆ Bus fault tolerance voltage range: ±58V

◆ Working voltage: 5V

◆ Working temperature range: -40℃-150℃

◆ Transmission distance (high-speed CAN): maximum about 40 meters (under 1Mbps)

◆ Data transmission rate (high-speed CAN): up to 1Mbps (CAN), 5Mbps (CAN FD)

◆ Characteristic impedance: 120Ω (Dip switch control, default closed, open access when the dip switch is ON)

◆ Bus port electrostatic discharge (ESD) protection capability: Human body discharge model (HBM) Up to ±8kV

(It is recommended to open the module schematic and look at the real object at the same time)

There is an LED power light on the module, which is always on after power-on

SW1 is a dip switch, which controls whether the 120Ω resistor is connected to the end of the CAN to form a closed loop. It is closed by default. When the two modules communicate,

one of the dip switches must be in the open state (the access is enabled when the dip switch is ON), or both are turned on, depending on the actual situation

D1 and D2 are TVS diodes, which are used to protect the CAN interface from electrostatic discharge (ESD), electrical fast transients (EFT) and transient voltages caused by lightning

U2 SIT1042AQT/3 transceiver

VCC: Connect to 5V power supply

VIO: Transceiver I/O level conversion power supply voltage, the lead pin is EN, and the EN pin is not connected in most cases. The level of RXD and TXD is provided by the master control. When RXD and TXD need to input and output specified voltages, connect to the EN pin. At this time, RXD and TXD The voltage is affected by the voltage connected to the EN pin. GND: grounding. S: for STB, high-speed mode and standby mode selection, the default grounding uses high-speed mode. TXD: transmitter data input terminal, connected to the TXD of the master control. RXD: receiver data output terminal, connected to the RXD of the master control. CANH: high-potential CAN voltage input and output terminal. CANL: low-potential CAN voltage input and output terminal.