Abstract: A system for transmitting data characters from a communication channel to a datascope for displaying the data characters on a CRT screen includes a plurality of switch members settable to a position for identifying a predetermined source of the data message to be displayed. When a data message is transmitted over the communication channel, a plurality of comparator circuits detect the start of the data message and the source of the data message. Logic circuits add end of message characters to the data message and identify a character in the data message to be highlighted on the CRT screen when a collision occurs between two remote sources of data messages which are attempting to transmit a data message over the communication channel at the same time.