Solution:

First we would like to explain how PCL-816 reads data from PCLD-789D. PCLD-789D is a multiplexer board, the channel on PCLD-789D needs to be switched with the digital output signals from PCL-816 20-pin D/O connector. Since the channel need to be switched with D/O, you cannot use DMA data transfer feature since DMA data transfer cannot switch the channel on PCLD-789D automatically. The process to read data would be like: 1. Set D/O data to select input channel on PCLD-789D, the D/O dara ranged from 0 to 15. 2. Have a short dealy, 10us typically, to allow the multplexer and amplifer being stable on PCLD-789D. 3. Read data from the A/D channel selected on PCLD-789D jumper JP2. For example, if channel 0 is selected with JP2, you should read PCL-816 channle 0 data with software trigger. 4. Go back 1 for next channel. And the wiring configuration would be, connect the PCL-816 37-pin connector to PCLD-774 37-pin analog port with a D-sub 37-pin cable, and connect the PCL-816 digital output connector CN1 to PCLD-774 MASTER digital port CN10. Then for first PCLD-789D, connect SLAVE1 connectors (CN4, CN9) to its CN1and CN2 respectively. For 2nd PCLD-789D, connect SLAVE2 connectors (CN3, CN8) to its CN1and CN2. For 3rd PCLD-789D, connect SLAVE3 connectors (CN2, CN7) to its CN1and CN2. For 4th PCLD-789D, connect SLAVE4 connectors (CN1, CN6) to its CN1and CN2. With PCLD-774, you can connect up to 4 PCLD-789D. On PCLD-789D, you need to set JP2 to different channels in order for the PCL-816 to read data from different channel. If you want to connect more PCLD-789D, you can connect extra PCLD-789D from PCLD-789D which is connected to PCLD-774, with 37-pin cable. So each PCLD-789D connected to PCLD-774 can connect extra one PCLD-789D with 37-pin cable, and totally 8 PCLD-789D can be connected for max extension. Of coarse the JP2 on each PCLD-789D should be set to different channel.