How do I fix USER FATAL MESSAGE 740?

Question

How do I fix USER FATAL MESSAGE 740? This error is generated by Nastran when I try to run a BDF/DAT file of mine.

*** USER FATAL MESSAGE 740 (RDASGN)
     UNIT NUMBER     5 HAS ALREADY BEEN ASSIGNED TO THE LOGICAL NAME INPUT
     USER ACTION: CHANGE THE UNIT NUMBER ON THE ASSIGN STATEMENT AND IF THE UNIT IS USED FOR
                  PARAM,POST,<0 THEN SPECIFY PARAM,OUNIT2 WITH THE NEW UNIT NUMBER.
                  AVOID USING THE FOLLOWING UNIT NUMBERS THAT ARE ASSIGNED TO SPECIAL FILES IN MSC.NASTRAN:
                  1 THRU 12, 14 THRU 22, 40, 50, 51, 91, 92. SEE THE MSC.NASTRAN INSTALLATIONS/OPERATIONS
                  GUIDE SECTION ON MAKING FILE ASSIGNMENTS OR MSC.NASTRAN QUICK REFERENCE GUIDE ON
                  ASSIGN PHYSICAL FILE FOR REFERENCE.

Below is the head of my BDF file.

assign userfile='SUB1_PLATE.csv', status=UNKNOWN, form=formatted, unit=52
SOL 200
CEND
ECHO = NONE
DESOBJ(MIN) = 35
set 30=1008,1007,1015,1016
DESMOD=SUB1_PLATE
SUBCASE 1
$! Subcase name : DefaultLoadCase
$LBCSET  SUBCASE1       DefaultLbcSet
   ANALYSIS = STATICS
   SPC = 1
   LOAD = 6
   DESSUB = 99
   DISPLACEMENT(SORT1,PLOT,REAL)=ALL
   STRESS(SORT1,PLOT,VONMISES,CORNER)=ALL
BEGIN BULK
param,xyunit,52
[...]
ENDDATA

If the provided answer helped you, accept and upvote it to support the volunteers that help you here. If not, leave some feedback and better clarify your problem — Lies, Jan 10 '22 at 12:08

score 2 · Answer 1 · answered Jan 02 '22 at 23:06

Below is the solution

Correct

assign userfile='SUB1_PLAT.csv', status=UNKNOWN, form=formatted, unit=52

I shortened the name of CSV file to SUB1_PLAT.csv. This reduced the length of the line to 72 characters.

Incorrect

assign userfile='SUB1_PLATE.csv', status=UNKNOWN, form=formatted, unit=52

The file management section is limited to 72 characters, spaces included. The incorrect line stretches 73 characters. The nastran reader ignores the 73rd character and on. Instead of reading "unit=52" the reader reads "unit=5" which triggers the error.

|<--------------------- 72 Characters -------------------------------->||<- Characters are ignored truncated ->
assign userfile='SUB1_PLATE.csv', status=UNKNOWN, form=formatted, unit=52

References

MSC Nastran Reference Guide

The records of the first four sections are input in free-field format and only columns 1 through 72 are used for data. Any information in columns 73 through 80 may appear in the printed echo, but will not be used by the program. If the last character in a record is a comma, then the record is continued to the next record.

How do I fix USER FATAL MESSAGE 740?

1 Answers1