That is unfortunate as we had understood when we ordered we weere getting two non ESS PLC's the ESS oner was actually more expensive, but he ended up sending that instead?? Do you know what the actual differences are? we have been having trouble with the center board, so simply swapped the replacement into the damaged PLC and the machine is back up running. we were going to do the same with the other laser-bank next week, but only if the board is the same. Hopefully the ESS part is on the program board of the lower board instead of the center one, and not it being a totally different device. please let me know if you have any knowledge about this. Regarding replacing/upgrading the PLC's , it's not going to happen, so we need to just keep it plodding along as it is. the company needs this machine working, but i don't see them going through the expense of upgrading as the machine is a one-off prototype and the designer/builders are NLA!