Io.popen stucks and cmd gets not closed - ruby

Question

I call the method send_csr1 from the method send_crs with this line of code:
send_csr1(pipe.read,#username,#password)
The problem is that normally the next line of code would be executed:
pipe.close_write
But somehow it wont what results in that the cmd is never closed. When i close it manually i get the error:
in `read': Interrupt
from stack.rb:49:in `block in send_csr'
from stack.rb:45:in `popen'
from stack.rb:45:in `send_csr'
from stack.rb:88:in `block in <main>'
from stack.rb:87:in `each'
from stack.rb:87:in `<main>'
My question is what do i have to change in my code, that ruby surley closes the cmd?
My full code:
def send_csr
IO.popen('cmd', 'r+') do |pipe|
pipe.puts('cd C:/OpenSSL/bin')
pipe.puts('openssl.exe')
pipe.puts("req -config c:/OpenSSL/openssl.cnf -in #{#csr}")
send_csr1(pipe.read,#username,#password)
pipe.close_write
end
end
def send_csr1(text,user,password)
#conn.basic_auth(user,password)
#res = #conn.get do |request|
request.url "csr"
request.headers['Content-Type'] = 'text/plain'
request.body = "#{text}"
end
end