Hi, the FoxDoc should be updated to address the problem that you can't choose the Letterbug you want. You have additionaly to read documents about CPs, FCMs and FBMs to get an overview about the limitations to Letterbug assignments. It would be better to put this important topic Letterbug into B0400FA*.pdf where you already find some notes about it. Regards, Andreas extract of B0700AH_G.pdf: For an FCM100Et or FCM100E, the first four characters of the FBM DEV_ID parameter (SLOT) must match the first 4 characters of the FCM100Et or FCM100E name. For an FCP270 the last two characters of the 6 character DEV_ID must be the slot position number (01,02, ....,07,08 for the FBM230/232; 0A, 0B, 0C, or 0D for the FBM231/233). For a non-redundant FBM, the last two characters (03) reflect the physical position (slot 03) of the FBM in its associated baseplate (0). For a redundant FBM pair, the last two characters (0C) reflect the physical position (slot 0C) of the module pair in its associated baseplate (0). Refer to DIN Rail Mounted Subsystem User's Guide (B0400FA) for additional information. _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave