Extremely cheap gateway for automation. Compatible with millions SCADA solutions (running on android, windows, cloud services etc.). Also useful for home automation: arduino projects, energy meters, temperature sensors, lighting solutions, solar panels, garage door openers etc. Solution based on TP-LINK router WR703N running openwrt and opensource project modbusgw (you can find it on sourceforge). It's actually Modbus/TCP to Modbus/RTU gateway with endless possibilities like VPN, WiFi, 3,4G wireless using external dongle etc. (thanks to openwrt team). To cut price RS-485 transceiver conected to internal serial port, data direction pin control with NE555 timer (ask google RS-485 NE555). As device for automation, i put somehow all stuff (with disassembled stock PSU) to small and cheap DIN box. Device tested with different energy meters (about 5 brands), arduino, temperature and humidity sensors and all works very well.
RS-485 transceiver SN75176
Connectors and Accessories / Telecom and Datacom (Modular) Connectors