FAQ01084 of Programmable Controllers FAQ

Normally, C200H-RM[][][] (SYSMAC BUS) and C200HW-DRM21-V1 (DeviceNet) cannot be used together. The DeviceNet Master Unit checks for the existence of Remote Master Units. If Remote Master Units are detected, an E4 error is output, and communications are stopped. Other than communications, the system will operate normally.
A Configurator can be used to solve this problem, allowing C200H-RM[][][] (SYSMAC BUS) and C200HW-DRM21-V1 (DeviceNet) to be used together.

When using a Configurator with C200H or C200HX/HG/HE, do not use the same I/O Area words for C200H-RM[][][] and C200HW-DRM21-V1.
When using the CS, read the master parameters using a Configurator and rewrite them to the CPU Unit to clear the E4 error. The E4 error will be cleared just by writing the parameters to Master Units using the Configurator.

When using the CS, the problem can be solved by using CS1W-DRM21-V1 DeviceNet Unit.
When using together with a SYSMAC BUS Unit, it is recommended to use CS1W-DRM21-V1.