
AR4000 User’s Manual
11
LLL004001 – Rev 2.7
5. Serial Interface Specification
5.1 Hardware Port
The default serial port in the AccuRange 4000 is a standard RS-232 port, which
can be connected to an IBM or compatible 9 pin serial port. If the 422/485 option
is ordered, the serial cable contains the wire pairs for point-to-point full duplex
RS-422 communication. Data can be transferred at any of several baud rates, in
binary or ASCII format.
RS-232 and RS-422 Serial Port Wiring
5.1.1 Output Flow Control
If configured for RS-232, The interface board responds to two types of flow
control: Ctrl-S/Ctrl-Q and hardware CTS/DTR. If configured for RS422, only
Ctrl-S/Ctrl Q can be used, since wire pairs for CTS-DTR are not included. The
interface will always stop transmission if Ctrl-S is received, and will resume
when Ctrl-Q is received. RS-232 interface response to the DTR flow control
input is controlled by the Flow Control configuration parameter. If flow control
is enabled and the host computer sets DTR false, the sensor will stop
transmitting. If flow control is disabled, DTR will be ignored. If output is
suspended in the middle of a sample, the remainder of the sample will be
transmitted when DTR is asserted by the host, but subsequent samples may be
lost.
5.1.2 Input Flow Control
The sensor does not transmit Ctrl-S/Ctrl-Q. In the RS-232 configuration, if the
input buffer is in danger of overflowing, the CTS line will be brought false. To
assure no loss of command string data, the host system should respond to this
signal if transmitting command strings of more than 10 bytes, or allow 0.1
seconds between commands for command completion. The Flow Control
configuration parameter has no effect on the interface’s assertion of CTS.
Pin # RS-232 Function
RS-422 Function
1
NC
TxData-
2
TxData
3
RxData
4
DTR
RxData-
5
GND
GND
6
DSR (Connected to CTS)
NC
7
NC
NC
8
CTS
NC
9
NC
NC