GE fanuc SNP & SNP-X


Thread Starter

Wang Yun Bo

Hello, everyone,

I want to connect a touch screen (Fuji's or Easyview's or Digital's) to GE FANUC 90-70 PLC using RS485, but not successful. When i use 90-30 PLC, the communication can be built well.
From the view of serial communication (as I know), the only diffirence between the two PLCs is that 90-30 uses SNP & SNP-X protocols, while 90-70 uses SNP only.
Can anyone give me some information?

Craig Morton

What CPU and port on the CPU are you using. Some of the 90/70 CPU's use a version of SNP w/ a break pulse and other do not. This may be your problem. It would also help to know the model of the OIT.


Alex Pavloff

From the GE-Fanuc Series 90 Serial Communications Manual (GFK-0582c, available from their website):

"The SNP-X Protocol is a simple protocol that provides fast data transfer between GE Fa-nuc
PLCs and related equipment. SNP-X provides significantly faster data transfer than does the SNP protocol. However, the SNP-X protocol does not provide the extensive set of services available with SNP."


"The built-in serial port in Series 90-20 and Series 90-30 PLC CPUs operate as SNP and SNP-X slave devices using RS-485 only. When configured for SNP operation, a serial port on a Series 90-30 or Series 90-70 CMM module supports both SNP and SNP-X op-eration; each serial port can be configured to operate as either a master or slave
device utilizing either RS-485 or RS-232."

I guess you need a CMM module. Call your GE rep for details or call your touch screen rep and ask them for a different driver.

Alex Pavloff
Software Engineer
Eason Technology