The SNP and SNPX protocol to the 9030 and 9070 are over RS422.
On Interact HMIs, Com2 is configurable to support RS232/RS422/RS485. When the units are shipped, the com port is set to RS485 and must be changed to RS422. There are Dip Switches in the side of the unit that the Compact Flash card is plugged in. All of the switches are for Com2. Com1 is always RS232 and can not be changed.
There have been some issues with old 9030/9070 hardware not working with the new HMI hardware. Some of the PLCs may have issues with the data rate etc.. from the new chipsets used in the HMIs. If this happens, the only workaround is to replace the cable between the HMI and the PLC with a GE 90 series Programming cable and set the com2 to RS232. If the programming cable works from your PC with the programming software then it will work with the HMI set to RS232. The Programming cable has a built in RS232 to RS422 converter.
The PLC has an SNP ID that MUST match the text string NODE ID set in the Interact driver even if the connection is point to point. If the PLC looses its memory, that setting is not part of the PLC program (apparently so since it has come up several times from users) and it must be manually set from the PLC Programming software. This is NOT the PLC Target Name setting, it is the SNP ID Setting. Making those two match is a good idea for consistency sake.
The MSDOS version of Logic Master software - F2 then F3 to get to the SNP ID
Logicmaster 90-30/20/Micro Programming Software User’s Manual – September 1998 GFK-0466L
HMI Driver Setting