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Modbus and ASCII protocol Via ACE PLC RS232, RS485 and USB Ports

  Rs232, RS485 serial ports can be configured by vBuilder as Modbus RTU slave or ASCII. Also, USB port can be configured as Modbus RTU slave. For all ACE ! Each port can also be configured for a variety of baud rates, number of stop bits and parity. Serial ports that can be configured for either RS232 or RS485 have dedicated configuration selection for that purpose.

All serial ports and USB port support Modbus RTU protocol. The ACE are slave devices. The default device address is 1, but can be configured to any desired address via vBuilder. Modbus communications is autonomous and simply requires set up of address mapping, using vBuilder, as shown on the right. Once set up and connected, communications occurs automatically.
When configured for ASCII, the port will send and receive character (ui8) arrays, under program control, through the use of program blocks like those shown on the right.  

If you wish to know more about Modbus: Modbus on Wikipedia

Complete Modbus Guide

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