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The development of the new Control and Monitor system (CMS) for GMRT envisages improved architectural functionalities compared to the present online system and is being developed using state-of-the-art approaches with available off-the-shelf hardware components and software solutions. We present the details of the upgrade undertaken to build a more powerful and sophisticated system. We also present the design and performance details of sub systems like Monitor and Control Module (MCM) and its associated software. The CMS system controls and monitors the working of all the telescope subsystems like Analog receiver, Digital receiver back ends, Optical Fibre systems, Electromechanical systems like Servo and Feed position system and Sentinel systems etc. This system establishes the command and voice communication link over a high speed 1 Gbits/s digital optical fibre link between the Central building and the antennas over a distance of about 20 Kms. A new MCM card is being developed using a Rabbit 8 bit micro-processor with ADC support and 100 Mbits/s Ethernet communication link. The RFI performance of this card is also being presented. VOIP phone and Video camera facility will also be available in all the antennas for voice communication and security purposes. IntroductionThe GMRT consist of 30 large and fully steerable parabolic dishes of 45 metres diameter, each in Alt-Azimuth mount, with 12 antennas in a compact (1kmx1km) array and 18 antennas in the "Y" shaped array as shown in Figure 1. It allows simultaneous low resolution imaging of extended emission as well as high resolution imaging of fine scale structure. The weight of the moving structure of each antenna is 82 tons and its counter weight is 34 tons.The purpose of the CMS system is to Control and Monitor the working of all the GMRT subsystems like Analog receiver, Digital receiver back ends, Optical Fibre systems, Electro-mechanical systems like Servo and Feed Positioning systems (FPS) and Sentinel system.It provides user interfaces for the Telescope Operators, Astronomers and maintenance personnel in the Central Electronics Building (CEB). The operator is alerted in case any anomalous behaviour is detected. In case of severe fault conditions, safety procedures are also automatically initiated. Sufficient interlocks are implemented in the servo systems to avoid putting the telescope in a potentially dangerous situation due to human error. Safety precautions are also undertaken to automatically switch off the main AC power to the antenna shell if the temperature is beyond the normal set limit or if smoke or fire is detected by the sentinel system. Figure 1. GMRT Array configuration. 2. Features of new CMS system [1] -Dedicated high speed Ethernet/OF link to each antenna -1 Gbits/s. -High end PCs in CEB and each shell with proper EMI/EMC protection -Linux OS. -Intelligent MCM using latest Micro-controller -Rabbit RCM 4300 series -High speed (~ 60 MHz) . -SD Memory -2 GB, 2 MB of flash program memory, battery backed up SRAM of 512 KB, 12 bit ADC. -Periodic T...