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Chapter 3. Communications Operations of the BHT
3.4 Basic 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.
Direct-connect Interface
Synchronization
Transmission Speed
Transmission Code
Transmission Bit Order
Vertical Parity
JIS 8-bit codes
Optical Interface
2400, 9600, 19200, 38400,
57600, or 115200 bps
■ 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 10˚ 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.
300, 600, 1200, 2400, 4800, 9600,
19200, 38400, 57600, or 115200 bps
JIS 7- or 8-bit codes
Start-stop
LSB (Least significant bit) first
None
Even, odd, or none