Metrix GX1010 Notice De Fonctionnement page 125

7
8
9
Pins 2, 3 and 5 may be used as a conventional RS232 interface with XON/XOFF
handshaking. Pins 7, 8 and 9 are additionally used when the instrument is connected to the
ARC interface.
Using a simple cable assembly, a `daisy chain' connection system between any number of
instruments, up to the maximum of 32 can be made, as shown below:
The daisy chain consists of the transmit data (TXD), receive date (RXD) and signal ground
lines only. There are no control/handshake lines. This makes XON/XOFF protocol essential
and allows the inter-connection between instruments to contain just 3 wires. The wiring of
the adaptor cable is shown below:
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 ARC standard for the other interface parameters is as follows:
Start bits
Data bits
Parity
Stop bits
In this instrument, as with most other ARC instruments, these parameters are fixed.
5.1.2.2. ARC 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
interface control.
38 - II
RXD2 Secondary received data (see diagram)
TXD2 Secondary transmitted data (see diagram)
GND Signal ground
1
8
None
1
GX1010