Features: With 8 channels of RS485 communication, the R413D08 module is the perfect solution for your Modbus-RTU protocol and AT command needs. Under the AT command ,the maximum delay is 9999 seconds;Under the MODBUS command ,themaximum delay is 255 seconds AT commands can be made serialHyperTerminal (serialassistant) Enter; MODBUS commands can be made serialHyperTerminal (serialassistant) OR ''Modbus Poll'' Enter; With RS485 and RS232TTL dualbus interface;8pcs Output controlpins, 5VTTL level, low level (default) / high level output Specifications: Item:RS485 Modbus DC: 5V / 6V 24V Optional Operating Current : 10-15MA Support:RTU protocol AT instruction Length:approx 45mm/1.77in for Relay Switch Board PLCControl Note: Due to the problems of lighting effects and shooting angles, there will be certain tolerances in the product, please understand. Please allow 0-1cm error due to the manual measurment. Package includes: 1PC RS485 Modbus