Hi Sanjeev,

I'm really confused, you tell _distance was a function, but you declare it as data (EXTRN DATA) ???

Following the generates assembler code of X.C51 and Y.C51.
X.C51 use an external function and external data, which both are given from Y.C51

================================
; X.SRC generated from: X.C51


NAME    X

?PR?test?X           SEGMENT CODE
        EXTRN   CODE (ext_func)
        EXTRN   DATA (ext_val)
        PUBLIC  test
; #pragma src
;
; extern char data ext_val;
;
; extern void ext_func(void);
;
;
; void test( void )

        RSEG  ?PR?test?X
        USING   0
test:
                        ; SOURCE LINE # 8
; {
                        ; SOURCE LINE # 9
;       ext_func();
                        ; SOURCE LINE # 10
        LCALL   ext_func
;       ext_val++;
                        ; SOURCE LINE # 11
        INC     ext_val
; }
                        ; SOURCE LINE # 12
        RET
; END OF test

        END

===========================
; Y.SRC generated from: Y.C51


NAME    Y

?PR?ext_func?Y       SEGMENT CODE
?DT?Y                SEGMENT DATA
        PUBLIC  ext_val
        PUBLIC  ext_func

        RSEG  ?DT?Y
        ext_val:   DS   1
; #pragma src
;
; char data ext_val;
;
; void ext_func(void)

        RSEG  ?PR?ext_func?Y
        USING   0
ext_func:
                        ; SOURCE LINE # 5
; {
                        ; SOURCE LINE # 6
;       ext_val++;
                        ; SOURCE LINE # 7
        INC     ext_val
; }
                        ; SOURCE LINE # 8
        RET
; END OF ext_func

        END

============================

Peter