# Open a communications channel to a dmc2280 motor controller
# contName: controller name, eg dmc2280_controller1
# The host and port in the SICS configuration file will be used by default
proc connect {contName {host ""} {port ""}} {
  global channel
  upvar #0 $contName controller

  if {$host == ""} {set host $controller(host)}
  if {$port == ""} {set port $controller(port)}

  if [catch {socket $host $port} con] {
    error "Failed to connect to $contName IP($host) port($port)\n\
    $con\n
    Is the motor controller switched on? Are the network cables plugged in?"
  }
  set channel($contName) $con
  fconfigure $channel($contName) -buffering line -translation crlf -blocking true
}

# Send a dmc2280 command
proc sendCmd {chan cmd} {
  puts $chan $cmd
  set status [read $chan 1]
  if {$status == "?"} {
    error "error: dmc command $cmd failed"
  } else {
    return $status
  }
}

# Receive a dmc2280 command
proc receive {chan} {
  gets $chan line
  # Consume the following colon
  read $chan 1
  return $line
}