Binghamton, NY Nov ten, 2009 #7 I'm not familiar with meter operation, but I would suspect that it needs to send the switching voltages (13v for odd and 18v for even). And, if you have to see the opposite sats it must send out the 22khz tone. Robin Layton is https://dienphucthinh.webflow.io/posts/cap-quang-panduit-chinh-hang-tai-dien-phuc-thinh