Denso BHT-7500W, BHT-7500S Basic Communications Specifica- tions and Parameters, Synchronization

Chapter 3. Communications Operations of the BHT

3.4Basic Communications Specifica- tions and Parameters

3.4.1 Basic Communications Specifications

Listed below are the communications specifications when the BHT exchanges data with a host computer through the CU-7000 (optical interface) or direct-connect inter- face cable.

	Optical Interface	Direct-connect Interface
Synchronization	Start-stop
Transmission Speed	2400, 9600, 19200, 38400,	300, 600, 1200, 2400, 4800, 9600,
	57600, or 115200 bps	19200, 38400, 57600, or 115200 bps
Transmission Code	JIS 8-bit codes	JIS 7- or 8-bit codes
Transmission Bit Order	LSB (Least significant bit) first
Vertical Parity	None	Even, odd, or none

■Synchronization

For accurate data transaction, it is very important to synchronize the transmission between the sender and receiver. To do this, it is required to previously define the bit order and position, the character length, and the beginning and end of the character to be transmitted.

The start-stop synchronization is an asynchronous system which synchronizes each character as a unit; that is, it externally adds start and stop bits to the leading and trailing bit positions of the character to be transmitted, respectively. A clock starts counting on receiving the start bit and it falls into a non-communication state on receiving the stop bit. The number of the stop bits is selectable (1 or 2 bits).

■Transmission Speed

Maximum number of bits to be transmitted per second. Expressed in bps (bits per second).

■Optical Interface Communications Range

The optical interface's maximum effective range is 80 cm (31.5 in.) with the IR beam within a 10û angle of divergence.

■Switching Time between Sending and Receiving on Optical Interface

The optical interface should satisfy the following requirements in switching be- tween sending and receiving:

(1)Within 10 ms from completion of sending, the optical interface should become ready to receive.

(2)After 10 ms or more from completion of receiving, the optical interface should start sending.

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