The Modbus.dll will no longer be updated, and it is removed from FTP and CD.
  If you need Modbus library, it's recommended to use the nModbusCE.dll.
Comparison of nModbusCE.dll and Modbus.dll
  ========================================================================
  nModbusCE.dll (Recommended)        Modbus.dll
  ------------------------------------------------------------------------
  Development tools            .net CF                 .net CF / EVC
  
  Modbus/TCP                 Master, Slave              Master Only
  
  Modbus/RTU                 Master, Slave              Master Only
  
  Modbus/ASCII               Master, Slave              Master Only
  ========================================================================
The location of nModbus SDK libary is on
  Path = CD:\napdos\wp-8x4x_ce50\SDK\Modbus
  FTP  = ftp://ftp.icpdas.com/pub/cd/winpac/napdos/wp-8x4x_ce50/sdk/modbus
The location of nModbus demos are on
  Path = CD:\napdos\wp-8x4x_ce50\Demo\Modbu
  FTP  = ftp://ftp.icpdas.com/pub/cd/winpac/napdos/wp-8x4x_ce50/Demo/modbus
The location of nModbus reference document is on
  Path = CD:\napdos\wp-8x4x_ce50\SDK\Modbus
  FTP  =  ftp://ftp.icpdas.com/pub/cd/winpac/napdos/wp-8x4x_ce50/sdk/modbus
If you still need Modbus.dll, please send email to us for assistance.
Service email: service@icpdas.com