Types and related parameters of Mitsubishi PLC synchronous encoders

The definition of a synchronous encoder axis is: a synchronous encoder axis is used when the input axis is driven by the input pulses of an externally connected synchronous encoder.

For example, in a system, the conveyor shaft is used as the main shaft, and the conveyor is controlled by a frequency converter. Then a synchronous encoder can be added to the shaft controlled by the frequency converter and used as the input shaft: the synchronous encoder shaft.

For example, in another case, suppose that the 16 axes controlled by the Mitsubishi PLC module QD77MS need to be synchronously controlled, but the spindle is a Mitsubishi servo amplifier controlled by other modules or other systems. In this case, it cannot be used as a servo input axis, but needs to be input through the Mitsubishi PLC synchronous encoder axis.

An example of using an external encoder as input axis synchronous control is shown below:

Types and related parameters of synchronous encoders

There are three types of input axes: command generation axis, servo input axis, and synchronous encoder axis.

There are also three types of synchronous encoder axes.

First, as shown in the figure below, the external synchronous encoder can be connected to the control system of Mitsubishi PLC Q172DS Motion in the following three ways. The input pulse of the externally connected synchronous encoder drives the input axis, and the status of the synchronous encoder can be monitored after the power is turned on.

In the synchronous control parameters, you can first select the input axis parameters as follows:

In the synchronous encoder axis parameters, you can select the three corresponding types as shown below:

1. Synchronous encoder Pn

The INC synchronous encoder connected to the manual pulse generator/INC synchronous encoder input of the Mitsubishi PLC simple motion module is used as a synchronous encoder axis.

When using the synchronous encoder type, you can choose to input through the encoder of the Motion built-in interface, the Q172DEX synchronous encoder input module, or the Q173DPX hand pulse input module. The control diagram is as follows:

01. Synchronous encoder through servo amplifier

The serial absolute synchronous encoder (Q171ENC-W8) connected to CN2L of the Mitsubishi servo amplifier (MR-J4-B-RJ) and the ABS/INC scale are used as the synchronous encoder axis.

When the synchronous encoder type is used by the servo amplifier, the control diagram is as follows:

Note: When the encoder is synchronized via a servo amplifier, the serial ABS synchronous encoder (Q171ENC-W8) connected to the servo amplifier full-closed loop MR-J4-B-RJ model CN2L is used as the synchronous encoder axis.

02. Through soft components

This is used when controlling a Gray code encoder connected to the input module of a Mitsubishi PLC module as a synchronous encoder axis.

When the CPU synchronous encoder type is used through soft components, the control diagram is as follows:

Synchronous encoder as input axis synchronous control experiment

Next, a simple experiment is used to demonstrate the use of the synchronous encoder.

2. Hardware Configuration

CPU:Q04UDEHCPU

Motion controller: Q172DS Motion

Mitsubishi servo amplifier: MR-J4-10B*2

Here, we use Q172DPX to input an incremental encoder, with a default encoder resolution of 400 pulse/r. The control framework and actual encoder diagram are as follows:

3. Synchronous control parameter settings

In the input axis parameters, select the synchronous encoder axis parameters, mainly need to set the synchronous encoder No. and unit conversion settings. Here we want to set the encoder to 10000 pulse/r, so the settings are as follows:

It should be noted that in unit conversion, the numerator and denominator parameter settings are more important, and the formula is as follows:

Therefore, when the original encoder resolution is 400 pulse/r input, if you want 10000 pulse/r output, the calculation formula is as follows:

10000 pulse/r = 400 x (numerator 100)/(denominator 4)

So the following settings were made:

Finally, in the synchronization parameters of axis 1 and axis 2, just set them to synchronous encoder input.

The above settings of Mitsubishi PLC synchronous control parameters, other configurations are the same as ordinary synchronous control parameters. It should be noted that the unit conversion parameters in the Mitsubishi servo encoder parameters should be understood and calculated, so that the servo axis can follow the external synchronous encoder for synchronous control.