Rs232 Character Set; Addressable Rs232 (Arc) Interface Control Codes - TTI QL Serie Manual De Instrucciones

All instruments on the interface must be set to the same baud rate and all must be powered on,
otherwise instruments further down the daisy chain will not receive any data or commands.
The other parameters are fixed as follows:
Start Bits: 1
Data Bits: 8

RS232 Character Set

Because of the need for XON/XOFF handshake it is possible to send ASCII coded data only; binary
blocks are not allowed. Bit 7 of ASCII codes is ignored, i.e. assumed to be low. No distinction is
made between upper and lower case characters in command mnemonics and they may be freely
mixed. The ASCII codes below 20H (space) are reserved for addressable RS232 interface control. In
this manual 20H, etc. means 20 in hexadecimal

Addressable RS232 (ARC) Interface Control Codes

All instruments intended for use on the ARC bus use the following set of interface control codes.
Codes between 00H and 1FH which are not listed here as having a particular meaning are reserved
for future use and will be ignored. Mixing interface control codes inside instrument commands is not
allowed except as stated below for CR and LF codes and XON and XOFF codes.
When an instrument is first powered on it will automatically enter the Non- Addressable mode. In this
mode the instrument is not addressable and will not respond to any address commands. This allows
the instrument to function as a normal RS232 controllable device. This mode may be locked by
sending the Lock Non-Addressable mode control code, 04H. The controller and instrument can now
freely use all 8 bit codes and binary blocks but all interface control codes are ignored. To return to
addressable mode the instrument must be powered off.
To enable addressable mode after an instrument has been powered on the Set Addressable Mode
control code, 02H, must be sent. This will then enable all instruments connected to the ARC bus to
respond to all interface control codes. To return to Non-Addressable mode the Lock Non-
Addressable mode control code must be sent which will disable addressable mode until the
instruments are powered off.
Before an instrument is sent a command it must be addressed to listen by sending the Listen
Address control code, 12H, followed by a single character which has the lower 5 bits corresponding
to the unique address of the required instrument, e.g. the codes A-Z or a-z give the addresses 1-26
inclusive while @ is address 0 and so on. Once addressed to listen the instrument will read and act
upon any commands sent until the listen mode is cancelled.
Parity: None
Stop Bits: 1
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