I have a PLC5 equipped with two 1771 DB/B cards. One of the cards is diplaying a continuous red led BTL. What does this indicate about my PLC's operation or programmed communication set-up?
The Battery Low (BTL)indicator is on. Replace it, before it is too late. There is also a reset button under the wire arm tab. If the battery is bad and you shut off power you probably lost the program. Good luck