We have a NI-DAQ 6508 that we are using for controlling relays. The manual says that the switch in the back controls the initialization state. While the initialized state matches the manual, the problem is that you must first configure a register to use it. The configuration seems to set the register to the logic low state, no matter what the switch is set to. Futhermore, you have to initialize the 3 registers of an 8255 before you can send data. In our case this means that large numbers of relays are active and creating undesired states before we can control them because we thought the initialization would be to what the switch indicated. What we do is initialize one 8255 and send data to it, initialize another 8255 and send
data to it, ... . This isn't completely satisfactory. Is there a better way to do this so that the relays are always in the off state?