---
title: I am using Modbus RTU control on the AR series with built-in positioning function. After turning the START input bit ON and running the controller, do I need to turn it OFF?
description: After turning the START input bit ON and operating, it must be turned OFF. A positioning operation is executed when the START input bit in the driver input command of the operation command changes fro
---

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# I am using Modbus RTU control on the AR series with built-in positioning function. After turning the START input bit ON and running the controller, do I need to turn it OFF?

After turning the START input bit ON and operating, it must be turned OFF.

A positioning operation is executed when the START input bit in the driver input command of the operation command changes from 0 (OFF) to 1 (ON). To execute the next positioning operation, the START input bit must also change from 0 (OFF) to 1 (ON).

Therefore, the START input bit must be set to 0 (OFF) before executing the next positioning operation or any other operation.

Operation command - Driver input command

![AR\_remoteIO](https://faq.orientalmotor.com/hs-fs/hubfs/AR_remoteIO.png?width=688&height=160&name=AR_remoteIO.png)See the timing chart below for the timing at which the START input bit is set to 0 (OFF).

Driving Instructions

① Verify that the READY output is ON.

② Select the operation data number with the M0 to M5 inputs and turn the START input ON.

③ The motor starts positioning operation.

④ Verify that the READY output is OFF, then turn the START input OFF.

⑤ When the positioning operation is completed, the READY output turns ON.

![AR\_timing2](https://faq.orientalmotor.com/hs-fs/hubfs/AR_timing2.png?width=688&height=351&name=AR_timing2.png)

![AR\_timing](https://faq.orientalmotor.com/hs-fs/hubfs/AR_timing.png?width=688&height=468&name=AR_timing.png)

 

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