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Ext. Reset
If the reset input is connected more than 3 seconds to ground GND or the RESET key is pressed at
least 3 seconds, a reset is carried out at the webserver as well as at the modem module.
Terminal No.:
Designation:
5
GND
6
Reset
Inputs (IN1, IN2)
The two digital inputs are fitted internally with pull-up resistors and are activated by connecting them
to GND. On activation, digital input 1 (IN1) dials into the internet via the set parameters. Digital input
2 (IN2) deactivates the installed modem to enable null modem operation via COM 1.
Terminal No.:
Designation:
7
GND
8
IN1
9
IN2
10
GND
COM 0 - W&T RS485 bus (W&T - RS232)
The serial interface is activated as RS485 port by setting a coding jumper (RS485 enable – GND). At
the same time the RS232 interface via DSUB plug is switched off. Without the coding jumper this
interface works as standard RS232 via the DSUB connection.
Double data lines A and B are connected to the terminals so that the internally existent pull-up, pull-
down and bus terminating resistors can easily be wired externally, if required.
If the ChemWeb Server is located at an end position of the RS485 bus, the terminating resistor
"Termination" (11) has to be connected to A (15). If the device is coupled in the bus center,
"Termination" must remain open.
At least at one point of the bus, the data lines should be connected to B by means of resistor Symm
(+) and to A by means of resistor Symm (-) in order to avoid floating of the data lines.
Terminal No.: Designation:
11
Termination
12
Symm (-)
13
Symm (+)
14
B
15
A
16
B
17
A
18
RS485 enable Switchover RS485 - RS232
19
GND
Explanation:
Ground
Input for external reset of ChemWeb Server
Explanation:
Ground
Digital input 1 – Dialing into internet
Digital input 2 – Switching over to null modem operation
Ground
This DSUB connection must not be used in the case of RS485
operation!
Description:
Bus terminating resistor (at end of RS485 bus)
Balancing resistor 1 (1 x in RS485 bus)
Balancing resistor 2 (1 x in RS485 bus)
Data line B
Data line A
Data line B
Data line A
Ground
3
Overview of ChemWeb Server
MG/L 5
Connection
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Terminal 20
Terminal 21
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