Serial Asynchronous Communications between Two Different Nuclear Medicine Computer Systems

A serial asynchronous communications interface has been established between a VIP 550 (Ohio Nuclear) and a GAMMA 11 (Digital Equipment Corp.) nuclear medicine computer systems. Data is transmitted either as a variable length ASCII character string (80 bytes) or as a block of 520 bytes (512 bytes of data plus control information and checksum). Data transmission is interlocked; each block of data transmitted from the GAMMA 11 elicits a response from the VIP 550. After initial handshaking, the GAMMA 11, which functions as a remote VIP 550 console, initiates an interaction by transmitting a command to the VIP 550. This command can be either part of the normal VIP repertoire or a command to transmit or receive a 256 × 256 frame of data. VIP format data is sent one line at a time with an acknowledgement after each line. The data is transformed in the GAMMA 11 to GAMMA 11 format. The GAMMA 11 study description block determines the number of frames which must be transmitted or received. Major areas for improvement include increasing the slow transmission rate (9600 baud) and adoption of a standard communications protocol.