Abaqus Definition of RHS in UEL Subroutine for 2D Truss element

I have a simple UEL subroutine with a 2D truss element. The element has two nodes: 11 (down) and 12 (up). The nodes are connected from bottom to top. Boundary conditions: node 11 has pinned support; node 12 has a roller (x-direction is blocked). The truss element is loaded by applying displacement U in the positive Y-direction at node 12.
Below, you can find my UEL subroutine and a sketch of the problem:

The issue is, that the sign of calculated in UEL reaction forces do not coincide with results from .dat-File.

If I understand correctly, the RHS for this problem is equivalent to the internal forces of a truss element in the global coordinate system. I may be wrong, but I think that the internal forces of a truss element in the global coordinate system are equal to the reaction forces of the truss element.

To calculate the RHS, I follow this procedure:

Define the global displacement vector U_glob. This vector is equal to the displacement vector U [U(1), U(2), U(3), U(4)] which is calculated by Abaqus.
Define the local displacement vector U_loc. U_loc = T*U_glob. T is a transformation matrix.
Define the local force vector localF. localF = K*U_loc. K is an element stiffness matrix in the local coordinate system.
Define the global force vector globalF. globalF = tranT * localF. tranT is the transpose of matrix T.
RHS = globalF

As you can see in the output of the Abaqus commander, the reaction force at node 11 (RF11) is negative, and the reaction force at the top node 12 (N) is positive. Considering the direction of the applied loading U, the sign of the result is correct. However, in the dat-file, the reaction force at node 11 (RF2) is positive and at node 12 it's negative. This is an incorrect result.

I also have a reference element T2D2 (nodes 1-2) in Abaqus CAE to verify the results. As you can see in output from dat-File, the sign is correct.

Do you have any suggestions to resolve my question?

Many thanks in advance!

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C The Fortran code below represents a User Defined Truss Element
SUBROUTINE UEL(RHS,AMATRX,SVARS,ENERGY,NDOFEL,NRHS,NSVARS,
1 PROPS,NPROPS,COORDS,MCRD,NNODE,U,DU,V,A,JTYPE,TIME,
2 DTIME,KSTEP,KINC,JELEM,PARAMS,NDLOAD,JDLTYP,ADLMAG,
3 PREDEF,NPREDF,LFLAGS,MLVARX,DDLMAG,MDLOAD,PNEWDT,
4 JPROPS,NJPROP,PERIOD)

INCLUDE 'ABA_PARAM.INC'
 
DIMENSION RHS(NDOFEL,NRHS),AMATRX(NDOFEL,NDOFEL),
1 SVARS(NSVARS),ENERGY(8),PROPS(*),COORDS(MCRD,NNODE),
2 U(NDOFEL),DU(MLVARX,*),V(NDOFEL),A(NDOFEL),TIME(2),
3 PARAMS(3),JDLTYP(MDLOAD,*),ADLMAG(MDLOAD,*),
4 DDLMAG(MDLOAD,*),PREDEF(2,NPREDF,NNODE),LFLAGS(*),
5 JPROPS(*)

C This is a UEL Subroutine for a Truss Element
integer i, j, m
integer, parameter :: ikind=selected_real_kind(p=8)
real(kind=ikind):: COSINEBETA, SINEBETA, L, F
real(kind=ikind):: K(2,2), T(2,4), tranT(4,2)
real(kind=ikind):: midK(4,2), globalK(4,4)
real(kind=ikind):: localF(2,1), globalF(4,1), U_loc(2,1), U_glob(4,1)
 
E = PROPS(1)
AREA = PROPS(2)
 
x1 = COORDS(1,1)
write(*,*) 'x1 =', x1
y1 = COORDS(2,1)
write(*,*) 'y1 =', y1
x2 = COORDS(1,2)
write(*,*) 'x2 =', x2
y2 = COORDS(2,2)
write(*,*) 'y2 =', y2
write(*,*) 'COORDS =', COORDS

C Calculating the length of the truss element

L = sqrt((x2-x1)**2 + (y2-y1)**2)

COSINEBETA = (x2-x1)/L
SINEBETA = (y2-y1)/L

C Zeroing the stiffness matrix

DO K1 = 1, NDOFEL
DO KRHS = 1, NRHS
RHS(K1,KRHS) = ZERO
END DO
DO K2 = 1, NDOFEL
AMATRX(K2,K1) = ZERO
END DO
END DO

C Defining a local stiffness matrix

K(1,1) = E*AREA/L
K(1,2) = -E*AREA/L
K(2,1) = -E*AREA/L
K(2,2) = E*AREA/L

C Printing the local stiffness matrix

write(*,*) 'local stiffness matri: K ='
 
do i = 1, 2
print *,(K(i,j), j = 1,2)  
end do
 
write(*,*)''
C Defining a transformation matrix

T(1,1) = COSINEBETA
T(1,2) = SINEBETA
T(1,3) = 0
T(1,4) = 0
T(2,1) = 0
T(2,2) = 0
T(2,3) = COSINEBETA
T(2,4) = SINEBETA

C Printing a transformation matrix
write(*,*) 'transformation matrix: T ='
 
do i = 1, 2
print *,(T(i,j), j = 1,4)  
end do
 
write(*,*)''

C Calculation of the transpose of a transformation matrix

do i=1, 2
do j=1, 4
tranT(j,i) = T(i,j)
end do
end do
 
write(*,*) 'transpose of a transformation matrix T: tranT ='
 
do i = 1, 4
print *,(tranT(i,j), j = 1,2)  
end do
 
write(*,*)''  
 
C midK is the multiplication of tranT and K, so tranT*K

do i=1, 4
do j=1, 2
midK(i, j) = 0.0
do m=1, 2
midK(i,j) = midK(i,j) + tranT(i, m)*K(m, j)
end do
end do
end do
 
 
write(*,*) 'multiplication of tranT and K, so tranT*K ='
 
do i = 1, 4
print *,(midK(i,j), j = 1,2)  
end do
 
write(*,*)''

C globalK is the global stiffness matrix of a truss element

do i=1, 4
do j=1, 4
globalK(i,j) = 0.0
do m = 1, 2
globalK(i,j) = globalK(i,j) + midK(i, m) * T(m, j)
end do
end do
end do
 
write(*,*) 'global stiffness matrix of a truss element, globalK ='
 
do i = 1, 4
print *,(globalK(i,j), j = 1,4)  
end do  
 
write(*,*)''

C Normal implicit time incrementation procedure

IF (LFLAGS(3) .EQ. 1) THEN

C Static automatic and direct incrementation

if(LFLAGS(1) .EQ. 1 .OR. LFLAGS(1) .EQ. 2) THEN
AMATRX = globalK
 
write(*,*) 'AMATRX ='
do i = 1, 4
print *,(AMATRX(i,j), j = 1,4)
end do
write(*,*)''

C Defining the global displacement vector

U_glob(1,1) = U(1)
U_glob(2,1) = U(2)
U_glob(3,1) = U(3)
U_glob(4,1) = U(4)
 
write(*,*) 'U_glob='
! Printing the resulting U_glob matrix
DO I = 1, 4
WRITE(*,*) U_glob(I, 1)
END DO
 
C Defining the local displacement vector
 
do i = 1, 2
U_loc(i, 1) = 0.0
do j = 1, 4
U_loc(i, 1) = U_loc(i, 1) + T(i, j) * U_glob(j, 1)
end do
end do

! Printing the resulting U_loc matrix  
write(*,*) 'U_loc='

do i = 1, 2
write(*,*) U_loc(i, 1)
end do

C Defining the local and global force vector

localF(1,1) = K(1,1)*U_loc(1,1) + K(1,2)*U_loc(2,1)
localF(2,1) = K(2,1)*U_loc(1,1) + K(2,2)*U_loc(2,2)
 
print *, 'localF= ', localF

do i=1, 4  
globalF(i, 1) = 0.0
do j=1, 2
globalF(i,1) = globalF(i,1) + tranT(i,j)*localF(j, 1)
end do
end do  

C Identifying the right hand side force vector
 
RHS = globalF
 
print *, 'RHS=globalF=Reaction forces=', RHS
 
end if
end if
 
write(*,*)''
write(*,*)'U(2)=', U(2)
write(*,*)'U(4)=', U(4)
write(*,*)'END OF ONE ITERATION'
write(*,*)'********************'
write(*,*)''
 
RETURN
END
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Abaqus