Kramer USB serial communication script for the VS-611DT

kramer.ps1

# VS-611DT COMMUNICATOR
# Interface for communicating with Kramer switches via RS-232 Serial
# Ultimately this is a desperate attempt to not have to walk a quarter mile to unplug a box every other day
# Robin Universe [S]
# 05 . 08 . 2026

param(
	$IN = "#",
	$COM = "COM8",
	$BAUD = 115200
)

# We need to find the most likely USB device that matches the Kramer USB
function find-device {
	Write-Host -Fo Yellow " VS-611DT COMMUNICATOR: SEARCHING FOR VALID COM PORT... " -NoNewline
	$d = (Get-WMIObject Win32_PnPEntity | where {$_.name -match "USB Serial Device*"})
	$COM = $d.Name.split("(")[1].replace(")","")
	Write-Host -Fo Green " $COM "
	return $d
}

# Follows a procedure that 'unsticks' the USB driver after a reset
# NOTE: This doesn't work on accounts without elevated access! 
# Users with no elevated access must restart or replug the USB physically like a caveman
function restart-device($device) {
	Write-Host -Fo Yellow " VS-611DT COMMUNICATOR: RESET PROCEDURE. "
	Start-Sleep 2 
	Write-Host -Fo Yellow " VS-611DT COMMUNICATOR: DISABLE DRIVER. "
	$device | Disable-PnpDevice -Confirm:$false
	Start-Sleep 2
	Write-Host -Fo Yellow " VS-611DT COMMUNICATOR: ENABLE DRIVER. "
	$device | Enable-PnpDevice -Confirm:$false
}

# Configures the port, opens the connection, and returns it. Most of the stuff
# in here was just fucking around until I found a setup that works
function open-port($COM) {
	Write-Host " VS-611DT COMMUNICATOR: ATTEMPTING TO CONNECT VIA $COM "
	$port = New-Object System.IO.Ports.SerialPort $COM,$BAUD,None,8,one
	$port.ReadTimeout = 2000
	$port.WriteTimeout = 2000
	$port.Handshake = 2
	#$port.RtsEnable = $true
	$port.NewLine = "`n" # Same results with "`n and `r and `r`n"
	try { $port.Open(); Write-Host -Fo Green " CONNECTED! " } catch { Write-Host -Fo Red "`n STINKY! Failed to connect to serial port!"; break }
	return $port
}

# Sends out the formatted command, or dies trying
function send-com($port, $IN){
	try { $o = $port.Write("$IN") } catch [TimeoutException] { Write-Host -Fo Red "`n STINKY! Send command timed out!" }
}

# You would not believe how much of a pain in the ass it is to make this non-blocking
# Returns the last line or an error code (1 for timeout, 2 for dead connection)
function listen-port($port) {
	if ($port.IsOpen) {
		try {
			$a = $port.ReadLine()
			return $a
		} catch [TimeoutException] {
			return 1
		}
	} else {
		return 2
	}
}

$device = find-device
$COM = $device.Name.split("(")[1].replace(")","") # Hacky bullshit to get the COM#
$p = open-port $COM
$timeout = 1 # this was useful once but now im afraid to remove it

# The main loop. I could have done this cleaner, but EVERYTHING wants to be blocking
# in this context, so we need to play a bit dirty
while ($true) {
	$IN = Read-Host " #"

	if ($IN -eq "exit") {break} # Breaks out of the outer loop on 'exit' 

	while ($true) {
		send-com $p ("#"+ $IN +"`r`n" ) # Formatting specific to this interface
		$d = listen-port $p
		if ($d -eq 1) {
			$timeout = ($timeout - 1) # This is weird but it works and is stable
			if ($timeout -lt 1) { Write-Host "`r Connection timed out! `n" -NoNewline ; break }
		}  elseif ($d -eq 2) {
			Write-Host " Port not open! "; break
		} else {
			if ( $d -Match "@" ) { $n = $d.split("@")[1] } else { $n = $d } 
			Write-Host " [RECV] $n" -Fo Green; break # Message recieved
		}

		Start-Sleep -Milliseconds 50 # Don't eat the entire CPU
		
	}

	if ($IN -eq "reset") { # Device reset requires some special treatment
		Write-Host -Fo Yellow  " DEVICE RESET INITIATED. DISCONNECTING... "
		break 
	}

}

# Make sure we properly close the port and dispose of the buffer, without this
# subsequent connections have problems
Write-Host -Fo Yellow " VS-611DT COMMUNICATOR: DISCONNECTING FROM SERIAL PORT... " 
$p.Close()
$p.Dispose()

# Do our special reset procedure if requested
if ($IN -eq "reset"){
	restart-device $device
}

# I don't trust all of those closes driver actions to properly block the script for long enough
# to finish so I hold it here for a few breaths to feel better about myself
Start-Sleep 2