PCB Piezotronics 441A35, Installation And Operating Manual

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441A152 PEAK METER 8
Manual 23528 Rev. A
ECN 50523
Appendix A: RS-232 Control
For RS-232 communication, the port settings should be as follows:
General RS-232, DCE interface, XON/XOFF flow control,
Asynchronous protocol
Baud Rate 9600 Baud
Start Bits 1
Data Bits
8
Parity None
Stop Bits 1
The message format is as follows:
Start Byte
(0x02) Destination ID
(Rack/Slot) Command End Byte
((0x03)
Checksum
Start Byte STX (0x02) - marks the start of a new message.
Destination ID 16 bits - rack code (0-3 ASCII) followed by slot address (0-9 ASCII). Messages meant
for the master will have "MM" in this field.
Command
Contains the command followed by any associated data. See below for command
structure, and command set for examples.
End Byte ETX (0x03) - marks the end of the message.
Data Checksum 16 bits - the ASCII hex of the 8-bit sum, ignoring overflows, of all bytes in the message
including SOT and ETX bytes.
All messages sent to the rack will receive a response. A typical command transaction is shown below.
Host Rack
Command
ACK [data]
NACK [reason]
The ACK/NAK field conveys information concerning the delivery of messages. The results of command
operations are contained in the data field of an ACK message. NAK reason bytes are defined below.
Start Byte (0x02) ACK (0x06)
Data Field End Byte (0x03) Checksum
The format of an ACK message.