Hardware port
AAUI Ethernet port: Early versions required external receiver to be converted to RJ45; The later hardware comes with 10Base-T RJ45, with a speed of 10Mbps (half duplex), but does not support 100Mbps
RS-232 (RJ-11): Local configuration, firmware upgrade port, no business data communication
15 Pin D Sub RS-485: firmware download and maintenance port, not used for on-site business communication
Backboard electrical
Backplane 5V consumption: 700   mA (high power consumption, power supply selection needs to be calculated)
Optoelectronic isolation: 1500VAC
Working temperature: 0-60 ℃, IP20 inside the cabinet, does not support hot swapping
CPU firmware requirements: Complete functionality requires CPU firmware V6.50 or above; Low version CPU functionality is limited
Support protocol (key pitfalls)
SRTP (GE Private Protocol, must be supported)
Port TCP 18245; Used for Proficy ME programming download HMI、 Multiple 90-30 PLCs are interconnected; The server mode has a maximum of 16 concurrent connections.
EGD Ethernet global data: high-speed periodic data broadcasting between PLCs.
Modbus TCP (master/slave): firmware version restrictions
Only firmware versions FH and higher support Modbus TCP; The old version firmware only has SRTP and does not have Modbus TCP! Old equipment renovation often falls into this pit.
Modbus TCP default port 502, with a maximum of 8 concurrent connections.
core functionality
Extend Ethernet capability to 90-30
Many older 90-30 CPUs do not come with Ethernet ports, while CMM321 enables Ethernet programming downloads and SCADA/HMI docking on the upper computer.
Ethernet interconnection between PLCs
SRTP/EGD enables data exchange between multiple 90-30 devices; When the firmware is sufficient, Modbus TCP interfaces with third-party devices.
Independent coprocessor, communication tasks do not occupy CPU scanning time, and communication services are called through the COMMREQ function block ladder diagram.

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