AR-401-IO-0808R-U2 built-in TCP/IP interface and Two Channel of RS485, works as two transparent gateway channels with Modbus-TCP to Modbus-RTU converter and also as Remote Control Unit (RCU) to implement decentralized I/O expansion of Modbus I/O Module 256 digital input (DI) and 256 digital output (DO). The RCU function is important for huge scale system as the RCU function will allow AR-401-IO-0808R-U2 becomes Union Control Board over decentralized 256 DI and 256 DO. Moreover the application is suitable with combination of Polling-Free Auto Update Monitoring Status in which real-time status need to be exact.
| Features | As Transparent Data Transfer | As Remote Control Unit (RCU) |
| Two Transparent Gateway Channels with Modbus-TCP to Modbus-RTU converter function | CH1 & CH2 | X |
| One Transparent Gateway Channels with Modbus-TCP to Modbus-RTU converter function | X | CH 1 |
| One Modbus IO expansion channel with RCU function* that support up to 256 digital inputs and 256 digital outputs in which user can send control command directly to I/O module. | X | CH2 |
*Note : Control up to total 256 DI and 256 DO, Each I/O unit reserved connection of 16 DI and 16 DO.
Calculation:
AR-401-IO-0808R-U2 onboard reserved for 16DI + 16DO
CH2 wired up to 15 units of I/O Product, each unit reserved for 16DI + 16 DO; equal to240DI + 240DO
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Total 256 DI + 256 DO
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Requirements Chart
| Classify | Picture | Name | Version | Note |
| Hardware |  | Serial Devices Server / Modbus Gateway with I/O (8 Optical Isolation Input/8 Relay Output) | Standard Firmware as Transparent Data Transfer: APX727i3___V0502 8i8o 220104.STM and after | |
| Serial Devices Server / Modbus Gateway with I/O (8 Optical Isolation Input/8 Relay Output)
AR-401-IO-0808R-U2 | As Remote Control Unit (RCU): APX727i3___V0502 8i8o 220104 CH2_SCAN_RCU.STM | |||
| Serial Devices Server / Modbus Gateway with I/O (8 Optical Isolation Input/8 Relay Output)
AR-401-IO-0808R-U2 | As Remote Control Unit (RCU) includes Polling-Free Auto Update Monitoring Status feature: APX727i3___V0502 8i8o 220104 CH2_SCAN_ RCU DI_EVENT_XCHG.STM | |||
 | 401_MBox_V0301_210804.ISP and after | |||
 | RS485 Communication Output Module (16 Relay Output) | 401RO16_V0207_191107.ISP and after | ||
.png) | (17 Optical Isolation Input/9 Relay Output) | 401RO8DI16_V0207_211209.ISP and after |