Multiple 1756-L61 controllers can be installed in the same chassis to communicate with each other across the backplane but operate independently. 1756-L61 controllers can communicate across RS-232-C (DF1/DH-485 protocol), DeviceNet, DH+, ControlNet, & EtherNet/IP networks.To provide communication for a ControlLogix 1756-L61 controller, an appropriate communication interface module must be installed in the chassis. One Allen-Bradley 1756-L61 Series B Allen Bradley 1756-L61 ControlLogix Logix5561 Processor 2MB, FULLY TESTED, in excellent working and good cosmetic condition. THE ORIGINAL FIRMWARE HAS BEEN UPDATED TO REV. The Serial Number in the pictures has been altered for privacy purposes. Are subject to our Policies and Terms. PLC Hardware 11706 Garrison Forest Rd Owings Mills, MD 21117, USA. Mon-Fri: 8:30am - 8.00pm ET. Is an independent distributor of used refurbished and new surplus industrial automation and networking equipment. Or in any way affiliated with Cisco, HP, Rockwell Automation, Siemens and any other listed manufacturers. PLC Hardware sells hardware products only and does not re-sell software licenses. PLC Hardware respects intellectual property of others, and we ask our customers to do the same. Customer acknowledges and agrees that PLCH does not provide any operating system software or software right-to-use licenses with the products it sells. As PLC Hardware is not an Authorized Distributor of the products. All listed logos, trademarks or service marks are property of their respective owners. The item "Allen Bradley 1756-L61 /B ControlLogix Logix5561 Processor 2MB F/W 19.11 Qty" is in sale since Monday, March 11, 2019. This item is in the category "Business & Industrial\Industrial Automation & Motion Controls\PLCs & HMIs\PLC Processors". The seller is "baltisales" and is located in Baltimore, Maryland. This item can be shipped worldwide.