DollaTek 5PCS 5V MAX485 / RS485 Module TTL to RS-485 MCU Development Board

Does the job

I had to check the Max485 specs, to find what levels enabled each half of the chip.RO enable is active LOW and DI enable is active HIGH.This means that you tie them together and just have a single logic level to switch between TX and Rx.Not sure why there is pullups on the enables which would put it into Master Tx , rather than Slave Rx when used to sniff traffic on a EPEVER Solar controller modbus.Using like this the terminator resistor 120R (R7) must be removed so signal is not double terminated.I now need to find out why there is bad checksums now and again on a very short lead (1 metre) and whether its the EPEVER controller or the Poor Solar Guardian PC application or even the serial application used to monitor.Far too flippin long, luckily I had 2 dev boards to mount it , but worked instantly through a TTL isolated USB <> Serial DSD Tech dongle which also supplied the 5V

Well designed compact pcb and very good components and soldering. No deterioration or corrosion so well stored and transported. Performs equally well although the device which needed to be connected evades communication, ive checked thoroughly and its not due to this module (reviewed item) which is doing everything it should. I may have some problems with the selection of the data direction as one rs485 is only half duplex and im hoping to correct this using txdr output on a ft232 (gpio) pin later on. Many thanks for a excellent product.

I needed a lot of 485 DMX transceivers differential to non differential PCB, and by reconfiguring removing the pull up resistors on RE and DE and shorting them to ground it works perfect even at 3.3V supply. So Thanks for saving a lot of my time

Some of these had wobbly terminal posts - didn’t really affect them functionally, but there’s very little to work with when it comes to writing reviews!

Cheaper than I can buy the (genuine) Maxim (MAX485) chips alone, so perhaps the chip is not genuine. It easily enters a "latch-up" state and I wonder if it has significant protection against static discharge (important in any long-distance network). There are resistors to match the line impedance and to provide idle-state biasing, but their values (120Ω, 2x20kΩ) appear to be ill-considered since the idle-state (when nothing else drives the network) has insufficient difference between the A and B lines to ensure a well-defined logic state.