MAX485 from Maxim is a low-power transceiver intended for RS-485 and RS-422 applications. It is a half-duplex driver with a Unit Load (UL) rating of 1 and therefore you can have up to 32 MAX485s on a single RS-485 bus. The data rate is up to 2.5 Mbps. MAX485 is available in 8-pin packages of various forms and the typical supply voltage is 5V. Its IO voltage is also 5V which means you can interface it directly to any 5V microcontroller. There are many easy-to-interface breakout modules available for using MAX485 in your applications. One such module is the one that combines a MAX485 with a CD4069 hex inverter. The module features auto data direction control which eliminates the need for two extra GPIO pins. Instead, the direction of data transmission is automatically determined by the RX and TX pins states. So you only need the power supply lines and the TX and RX lines for interfacing. We have an in-depth RS485 communication tutorial using the same module which you can find below.
|Data Rate||2.5 Mbps|
|Data Rate at 1200 m||110 Kbps|
|Quiescent Current||300 uA|
|Number of receivers on the bus||32 (1 UL)|
|Working Voltage||3 – 12 V (5V typical)|
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|RE||Receiver Enable (Active LOW)|
|VCC||Positive supply voltage|
|GND||Negative supply voltage|
Latest Revision: Rev 0.1, 07-12-2022
Design by: Vishnu Mohanan
License: CC-BY-SA 4.0
Pinouts are based on the latest documentation from the manufacturer. While we try our best to be accurate and up-to-date here, we can not guarantee correctness. Please also double-check the pin assignments with that from the official documentation. If you found any errors here, please let us know in the comments. We will update our designs ASAP.
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|VCC||Positive supply voltage|
|RXD||Module data receive pin. Send data through this pin.|
|TXD||Module data transmit pin. Read data from this pin.|
|A+||Positive line of RS-485|
|B-||Negative line of RS-485|
When connecting one RS-485 module another RS-485 module you must only connect the A+, B- and SC lines. You don’t necessarily to share the VCC or GND supplies.
Below is a reverse-engineered schematic of the module.
- What is RS-485 & How to Use MAX485 with Arduino for Reliable Long-Distance Serial Communication – CIRCUITSTATE Electroncis
- MAX485 – Datasheet [PDF]
- CD4069 Hex Inverter – Datasheet [PDF]
- Original TIA/EIA-485 Standard Specification [PDF]
- RS-485 Serial Interface Explained – CUI Devices
- Explanation of Maxim RS-485 Features – Analog Devices
- RS485 Cabling – Why you need 3 wires for 2-wire RS485?
- Basics of RS-485 – Texas Instruments [PDF]
- RS-422 / RS-485 Industrial Standards
- What is RS-485 and how is it used in industrial control systems? – RealPars
- How do I wire RS485 devices? – Innon
- Wiring of RS485 Communications Networks – Schneider Electric
- Short URL to this page – https://www.circuitstate.com/max485pinout