22
WIKA operating instructions, model GDM-RC-100-T
EN
14499439.01 01/2022 EN/DE
5.4.1 Connection assembly (model GD-20-D)
■
Use a cable consisting of shielded twisted pair data lines with suitable characteristics for
the particular operating conditions.
■
Select a cable diameter that matches the cable bushing of the connector or the cable
socket. Make sure that the cable gland of the fitted connector or fitted cable socket has a
tight fit and that the seals are present and undamaged. Tighten the threaded connection
and check that the seal is correctly seated, in order to ensure the ingress protection.
■
Make sure that no moisture enters at the cable end
5.4.2 Pin assignment of attached, digital transmitter (model GD-20-D)
Circular connector M12 x 1 (5-pin)
1 -
-
2 U
+
Supply voltage
3 U
-
Ground
4 A
Signal RS-485
5 B
Signal RS-485
5.4.3 Pin assignment, integrated, digital transmitter (model GD-20-D)
Via 4-pin terminal in the cable socket, conductor cross-section 0.205 ... 2.5 mm
2
4-wire terminal in cable socket
U
+
DC 10 ... 30 V
U
-
Ground
A
RS-485 signal
B
RS-485 signal
5.4.4 Requirements for shielding and grounding
■
Only use shielded cables and connect the shield on one side to the read-out unit.
■
The gas density sensor is grounded via the process connection of the mechanical
base instrument.
■
Ensure that no earth circuits can occur.
5.4.5 RS-485
The physical layer for the Modbus
®
protocol is the serial RS-485 interface per
EIA/TIA-485. The differential signal between pins 4 and 5 (A and B) is evaluated with a
2-wire system (half-duplex).
5. Commissioning, operation