a. How can I specify the COM ports to use instead of relying on auto detection? let's say I have 6 units. I would like to do something like -d grid 3,4,5,6,7,8 where each would be the COM port.
I have two bfgminer instances running on a Raspberry Pi, one controlling Bitfury and BFL hardware for SHA256 mining and another controlling Gridseed hardware for scrypt mining. The config files for each are set to only look for the relevant hardware. bfgminer.conf.sha256 includes these statements (among others):
"scan" : [
"bfsb:auto",
"bitforce:/dev/ttyUSB0",
"bitforce:/dev/ttyUSB1"
],
"set-device" : [
"BSB:osc6_bits=52"
],
bfgminer.conf.scrypt, by comparison, includes these:
"scan" : [
"gridseed:/dev/ttyACM0",
"gridseed:/dev/ttyACM1",
"gridseed:/dev/ttyACM2",
"gridseed:/dev/ttyACM3",
"gridseed:/dev/ttyACM4",
"gridseed:/dev/ttyACM5"
],
"set-device" : [
"gridseed:clock=850"
],
Since the BFL and Gridseed miners are both USB devices, I needed to tell each instance which devices to use. (The Bitfury hardware is connected to the Raspberry Pi's GPIO header, so auto-detect works for that.) Something similar ought to be possible under Windows, but I don't have direct experience with mining on Windows as I've always used Linux for this purpose. You'd most likely want to replace occurrences of /dev/tty* with something else.