Hello,
Yes, you can use an SCB-68 with an NI 6251 and wire it according to the E Series full 68 pin pinout. The only differences between the full 68 pin E Series pinout and the 68 pin M Series pinout are:
1) With M Series, PFI0 no longer doubles as both an analog and digital trigger input. It is only a digital trigger input. APFI0, which is pin 20, is a dedicated analog trigger input on M Series. This pin is shared with the AO External reference input on M Series and corresponds to the AO External reference input on an E Series.
2) PFI15 on an M Series corresponds to a ground on an E Series.
The M Series pinout for your device can be found in the M Series Help, located in the following location:
http://digital.ni.com/manuals.nsf/display?ReadForm&lookup=Data%20Acquisition%3E%3EMultifunction%20DAQ%3E%3EM%20Series%20Devices&view=web_productcurrent&node=132090_US
Nicole
