Xylem SDI-12 Data Logger iLink - Manual (Page 11)

iLink - Configuration and Support Utility 11
[email protected] i Quest (NZ) Ltd - PO Box 15169 HAMILTON Tel: +64 7 957 8160 - Fax: +64 7 957 8162 - Email:
Retries
Defines the number of data packet retries before a communications failure (from the computer to the
device) is logged. A communications circuit will exist but the actual transfer of data will have been
unsuccessful. The default setting is 3.
Timeout:
Sets the timeout (in milliseconds) before a data packet retry is attempted. If using a low speed connection
ensure sufficient time is allowed for the data packets to be transferred successfully. Default time (ms) =
2000 at 9600bps.
CTS Delay:
This inserts a delay to await the communications channel to come clear after transmission. Default time
(ms) = 0 for direct RS232 connections. If the delay is zero, then CTS is ignored and transmission will
occur immediately.
Leading Chars:
This parameter is used to set the lead-in delay time. The actual delay (in seconds) is:
(number of characters) / (baud rate/10)
So for example, 60 leading characters at 1200 baud will give a 0.5 second lead-in time (500ms). For a
direct computer connection, set to 3.
Trailing Chars:
Sets the number of trailing characters to send after the actual data packet. For a direct computer
connection, set to 1.
The selection of baud rate, retries, timeout and leading/trailing characters are more significant if
communications is by a low speed communications link (e.g. radio), and may need to be adjusted
depending on the integrity and speed of the communications. These settings should only be changed if
communication problems are being experienced and a physical communications circuit can be proven to
exist. The table below gives typical settings for various connection methods.
Leading Characters Trailing Characters
Direct PC-Device Connection or
Modem connection across PSTN circuit
3 1
Radio or RS485 option where there may
be a problem with buffered UARTs
causing truncated packets where RTS
goes false before all characters are
transmitted with a modem connection
40 18
Connection using a 1200 baud radio
channel
60 3
PC’s Address: (Also referred to as iLink’s Address)
The default value is –5, which is a reserved address. Generally the PC Address will remain at this value.
If iLink is used to communicate with devices over a radio channel shared by
HydroTel, make sure iLink’s address is NOT set to 0 (Zero), as this is HydroTel
2000’s normal base address.
Communication Mode