Image forming apparatus, communication monitoring system, and communication monitoring circuit

Abstract

An image forming apparatus includes an image forming unit, a controller including a master unit and a slave unit, and a serial communication line connecting the master unit and the slave unit and used in serial communication. The master unit includes an arithmetic module that generates first serial data to be transmitted to the slave unit to monitor serial communication, and monitors whether the first serial data has been successfully received in accordance with second serial data received from the slave unit. The slave unit includes a pulse signal output module that outputs pulse signals for a number of pulses which is set from the first serial data, an analog voltage output module that receives the pulse signals, changes an analog voltage in accordance with the number of pulses, and outputs the analog voltage, and an analog / digital conversion module that converts the analog voltage into the second serial data.

Description

technical field [0001] The present invention relates to an image forming device, a communication monitoring system and a communication monitoring circuit. Background technique [0002] Japanese Unexamined Patent Application Publication No. 4-178048 discloses a transmission control circuit for bidirectionally transmitting serial signals. The transmission control circuit includes, on its receiving side, a serial-to-parallel converter circuit that parallelizes received signals and a memory that sequentially stores outputs from the serial-to-parallel converter circuit, and when appropriate, updates and registers the conditions of other transmitting ends in the memory, and reads The contents of the memory are fetched to determine the condition of the other sender. [0003] Japanese Unexamined Patent Application Publication No. 11-65603 discloses a dual-process input / output device which is a process connected to a control microprocessor unit (MPU) via an IO link to constitute a c...

AI Technical Summary

Problems solved by technology

However, the SPI communication standard does not specify a protocol for detecting communication errors using parity checks, cyclic redundancy checks (CRC), checksums, etc.

Therefore, in the case where data is unilaterally transmitted from the master controller to the slave controller, loss due to physical errors in the communication line, data deterioration due to external noise, distortion of wires (such as cables) constituting the communication line characteristic changes, etc., resulting in failure to obtain a certain level of signal waveform quality, and communication errors, etc.

Even in this case, the master cannot determine the condition of the slave

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