| 摘要 |
PURPOSE:To check easily and exactly the collision detecting and resending function of a terminal station in case when the detection is generated at the time of a simultaneous transmission from plural terminal stations by providing a test control part, a register, a selector, an AND gate and an operating part on a terminal station. CONSTITUTION:In case of testing the collision detecting and resending function of a terminal station 4', an operator starts a test control part 13 by an operating part 17 and sets, for instance, '1' to (f1) of a register 14. Subsequently, the AND gate 16 is opened through a selector 15 by a carrier non-detecting signal A from a detecting part 7. As a result, a data transfer control part 8 is started through a start signal ST from the control part 13 and a data D in a buffer memory 10 is sent out to a line 1. In this case, when a collision is generated on the line 1, a collision signal Q is outputted from the detecting part 7 and by this signal Q, the register 14 is reset. In this way, by providing the control part 13, the register 14, the selector 15 and the AND gate 16, etc., the collision detecting and resending function of the terminal station can be checked easily and exactly.
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