Rs232 Character Set; Addressable Rs232 (Arc) Interface Control Codes - Promax GR-205 Manuel D'instructions

5.3.4 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.

5.3.5 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.
Because of the asynchronous nature of the interface it is necessary for the
controller to be informed that an instrument has accepted the listen address sequence
and is ready to receive commands. The controller will therefore wait for Acknowledge
code, 06H, before sending any commands. The addressed instrument will provide this
Acknowledge. The controller should time-out and try again if no Acknowledge is
received within 5 seconds.
Listen mode will be cancelled by any of the following interface control codes
being received:
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USER'S MANUAL. GR-205
09/2004