I-O Display Systems Basic I/O Product - Manual (Page 76)

Setup 3
3-3(Vol.2)
Baud Rates:
Any One of the standard baud rates of 300, 600, 1200, 2400, 4800, 9600, 19200, or 38400 can
be used for the serial network communications. The sequential display indicates the letter H
followed by the baud rate divided by 100. Basic I/Os are shipped at 9600 baud; the sequential
display indicates H096. Changing the BASIC I/O AD baud rate is explained beginning on
page 3-4
Protocol Handshake Types:
Two protocol handshake types are available, 2 pass and 4 pass.
2 Pass: The host transmits an instruction to a BASIC I/O AD.
If the instruction is correctly received (i.e. valid address, instruction type and
correct checksum) the BASIC I/O AD executes the instruction and returns the
letter “A” and a cr or, where data is to be returned, the letter “A”, then the data,
followed by a two character checksum ending with a CR.
4 Pass: The host transmits an instruction to a BASIC I/O AD. If the instruction is
correctly received (i.e. valid address, but not necessarily the correct instruction
type nor checksum), the BASIC I/O AD returns an “A” followed by the Echo of
the instruction and does not execute it. If the host then transmits an E, the
instruction is executed in the same manner as the 2 pass. If the Hos transmits any
other character to any unit on the network, the instruction is disregarded
The sequential display indicates the letter P followed by 2 or 4. BASIC I/O ADs are shipped
in 2 pass mode; the sequential display indicates P2. The actual setting of the handshake
protocol type is detailed following network type switch.
Network Type Switch:
The digit after the “l” ion the sequential display represents how the network switch is set.
Note: The seven segment display will not reflect a switch position change until power has
been cycled to the unit.