Modbus Communication between CNC and PLC using Mach3 CNC Software

Video about the testing of Modbus communication between CNC and PLC using Mach3 CNC Software


A. Preparation for this application:
1. Free Download Mach3 CNC Software (click here) or http://www.machsupport.com/downloads.php and choose Lockdown
2. PLC Cable for Siemens S7-200 PLC
3. Siemens S7-200 PLC
4. Connect PLC Cable to Port 0 in Siemens S7-200 PLC

B. Modbus and Ladder Program in the PLC
Download PLC program (click here) and Upload to PLC. Or creating a ladder program as shown below and upload them to the PLC.

PLC Ladder for Modbus Communication 1
PLC Ladder for Modbus Communication 2 and 3
 PLC Ladder for Modbus Communication 4 and 5
PLC Ladder for Modbus Communication 6

1. Definition of ladder program for Network 1:
Assigns Port:
Mode =0 =>assigns port 0 to PPI and disable Modbus protocol
Mode = 1 => assigns port 0 to Modbus protocol and enables the Modbus protocol

Modbus Communication Setting in PLC:
Modbus Address Slave: 1 (Addr) =>Addr Values between 1 and 247
Modbus Baud Rate: 9600 (Baud) => Baud rate at 1200,2400,4800,9600,19200,38400,57600,115200
Modbus Parity: None (Parity = 0) => None Parity = 0, Odd Parity = 1, Even Parity = 2
Modbus Message Timeout: 20 (Delay)

Input, Output, Analog Setting:
MaxIQ: 128 => Number of I and Q Points available to Modbus Addresses (Value of 0 to 128). For disables MaxIQ=0.
MaxAI: 32 => 0 for CPU 221, 16 for CPU 222 and 32 for CPU 224, 224XP, 226, 226XM

Memory setting in PLC:
Input / Output Memory (Register) Holding, starting from: VB800 (HoldSt~)
Maximum Memory (Register) Holding: 100 (MaxHold) => Access the 100 Words of V memory Or 200 Bytes of V memory.
Input Output Memory Register Holding Modbus Protocol

2. Definition of ladder program for Network 3 and Network 4:
Network 3: Move Byte from VB801 to QB0 (Q0.0 to Q0.7)
Network 4: Move Byte from VB800 to QB1 (Q1.0 to Q1.7)
Move Byte of Ladder Program Siemens S7-200 PLC for Output Modbus Application

3. Definition of ladder program for Network 5 and Network 6:
Network 5: Move Byte from IB0 (I0.0 to I0.7) toVB803
Network 6: Move Byte from IB1 (I1.0 to I1.7) to VB802
Move Byte of Ladder Program Siemens S7-200 PLC for Input Modbus Application

C. Modbus and Mach3 CNC Software
Config Ports and Pins: 
setup modbus communication in mach3 cnc

Modbus Plugin Setting:
Modbus communication setting in mach3 cnc for Modbus plc communication

1. Modbus Communication Setting
Port Num: 3
Baud Rate: 9600
Data: 8 – 1 – N
2. Modbus Register Setting
2.1. Cfg #0:
Slave #: Address Slave Number in PLC (Addr = 1)
Direction: Output-Holding => Write from Mach3 to V memory PLC
2.2. Cfg #1:
Slave #: Address Slave Number in PLC (Addr = 1)
Direction: Input-Holding => Read from V memory PLC to Mach3
2.3. Address Modbus(Var) and # of Registers:
Address Modbus and Total of Registers


Video About How to Modbus Setup in Mach3 CNC Software

3. Modbus Access with Brains Mach3 CNC Software
Video about How to Create Brains in Mach3 CNC for PLC Output/Input Access with Modbus Protocol

Or download Brains file (click here) and Copy Paste to folder ...\Mach3\Brains , or default install Copy Paste to folder C:\Mach3\Brains
Brains file location in mach3 cnc

Brains View for Modbus Communication between PLC and Mach3 CNC
brains view mach3 cnc for modbus communication between plc and mach3 cnc

3.1. How to access the PLC Output with Modbus
Example:Write to PLC Output Q0.4
Write to PLC Output Q0 bit4

3.2. How to access the PLC Inputwith Modbus
Example:Read from PLC Input I0.1
Read from PLC Input I0 bit1
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