IP Relay HWg-ER02b - Manual
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Setting the connection length
Keeping a TCP socket open is
useful when small volumes of
data need to be transferred as
soon as they come in but HW
VSP is not used or a permanent
connection needs to be avoided.
For the duration specified by the B
option, the connection is kept
open and data are sent
immediately, without the delay for
establishing a TCP connection.
On the other hand, a long
timeout means a long period of
inaccessibility through other
sockets (disconnected cable,
TCP setup).
B: IP Protocol Retry
124
Determines the TCP connection timeout if no communication
takes place. Predefined values are available through the
asterisk notation:
*1: 30 s (n = 35)
*2: 1 min (n = 45)
*3: 2 min (n = 63)
*4: 5 min (n = 77)
*5: 10 min (n = 101)
*6: 15 min (n = 124)
*7: 30 min (n = 144)
*8: 1 h (n = 179)
*9: 2 h (n = 249)
The timeout can be fine-tuned by specifying a value from 10 to
255 according to this formula:
n <16 .. n * 0.2 s
n < 32 .. (n- 15)* 0.8 s + 3.0 s
n < 64 .. (n- 31)* 3.2 s + 15.8 s
n <128 .. (n- 63)*12.8 s + 118.2 s
n <256 .. (n-127)*51.2 s + 937.4 s
Example:
B42 => (42-31)*3.2+15.8 = 51s
V: NetworkVirtualTerminal
Off
Network Virtual Terminal enables interpretation of Telnet sequences, including certain RFC2217
extensions that enable on-the-fly changes of serial port parameters (speed, parity, etc.). NVT
description can be found at our website: >> “Support & download” >> “
NVT (Network Virtual
Terminal) protocol description
”.
When communicating with the serial port using telnet, e.g. with the TeraTerm program or the
Hercules utility, NVT should be enabled. If you don't want to use this option, set your client to “RAW”
communication mode.
0: Off
(do not use telnet control codes, pass through to serial port)
1: On
(accept telnet control codes)
Note:
With NVT off, it is not possible to control the digital inputs and outputs, and the SETUP does
not even show the corresponding settings.
K: Keep connection
Off
Keeps TCP connections alive to avoid automatic termination upon timeout specified by the
B:
parameter.
IP protocol retry time
. When enabled, the device sends a NVT NOP command
approximately every 5 seconds to check the connection state. If port sampling is enabled with the #T:
Trigger AND mask parameter, the device sends an I/O keep command (FF FA 2C 37 ..) instead of a
NOP (see #K, #L, #M, #N). NVT must be enabled for this parameter to take effect
– when NVT is off,
IP Relay repeats the last packet sent and the Keep function is dependent on the remote TCP
implementation.
0: no keep connection
(preferred)
1: keep connection
