Rice Lake Sartorius Midrics 1 and 2 Series - Installation Instructions - Manual (Page 8)

8
Configuring the Interface Module:
YDO01M-485, YDA01M-20MA
YDO01M-485 (Options A2 and A3)
Characteristics
The YDO01M-485 module (serial RS-485/RS-422 interface, electrically isolated
1 ) can be
operated with your choice of RS-485 or RS-422 protocol.
The module is configured by eight switches.
In addition to defining whether RS-485 or RS-422 is used, certain terminating resistors
(120
O) and/or bias resistors may have to be activated or deactivated, depending on
whether a network or point-to-point connection is used.
The positions of the switches are indicated in the drawing on the left. Close switches 1
through 4 for RS-422 operation.
The following list shows the functions of switches in the closed (“ON") position:
Function (on = closed) Switch
Terminating resistor, transmitting side 120 O 1 - 1
Bias resistor, transmitting side (TxD+, pull-up) 680 O 1 - 2
Bias resistor, transmitting side (TxD–, pull-down) 680 O 1 - 3
ON: RS-422 operation | open: RS-485 mode 1 - 4
Terminating resistor, receiving side 120 O 2 - 1
Bias resistor, receiving side (RxD+, pull-up) 680 O 2 - 2
Bias resistor, receiving side (RxD–, pull-down) 680 O 2 - 3
No function 2 - 4
Note on setting the switches:
Switches must be set pairwise as follows:
– Switches 1–2 and 1–3: both ON or both OFF
– Switches 2–2 and 2–3: both ON or both OFF
Operation as an RS-485 Interface (Option A3):
§ Switches 1 - 4 must be open to operate the module in RS-485 mode (factory setting).
§ If necessary, deactivate the bias resistors for the RS-485 mode. To do this, open the
switch (factory setting).
The bias resistors must occur no more than once per data transmission path (whether
over a network or in a point-to-point connection); otherwise, transmission errors may
occur. Please refer to the specifications or wiring diagram for the remote station or
network node in question for detailed information. Always activate or deactivate bias
resistors in pairs.
§ The terminating resistor (transmitting side, switch 1 – 1) must be activated if the device
is at either end of an RS-1 bus system, or when connected point-to-point with another
device. The remote station must also have a 120-
O terminating resistor. If necessary,
activate the terminating resistor (120 O) for RS-485 operation:
close switches 1 - 1 and 2 - 1 (“ON")
Operation as an RS-422 Interface (Option A2):
§ Close switches 1 - 4 for RS-422 operation (“ON")
§ If necessary, deactivate the bias resistors for RS-422-operation. To do this, open the
switches.
§ Activate the terminating resistor on the receiving side (switch 2 – 1), if no external termi-
nating resistor is available. Always deactivate terminating resistors on the transmitting
side (switch 1 – 1).
1 ) The shielding in the connecting cable is connected at one end to the housing of the indicator.
The indicator is connected to the protective grounding conductor.