Ct1; Rs-485 Interface - Bender LINETRAXX SmartDetect RCMS410 Manual

Interfaces
4.5.3 CT1...4 as digital input
Settings in registers 32300...32301
Alternatively, the inputs CT1...4 can also be used as digital inputs. In this event, the following
technical conditions must be met:
• The values of a potential-free contact are read in.
• < 100 Ω is considered "open";
• > 250 Ω is considered "closed";
• Current via switching contact: 0.6 mA.
The behaviour depends on the mode set (high-active or low-active):
• When the contact is closed with high-active: Main alarm
• When the contact is opened with low-active: Main alarm
With a main alarm the rms-value (min., max., and avg.) is output as 1, if there is no alarm as 0. The
other measured values are not affected. For an alarm to be output correctly at the corresponding
interfaces the corresponding RMS alarm assignment must be enabled.
4.6

RS-485 interface

Specification
The RCMS410 has an RS-485 interface with Modbus RTU protocol. In a system setup it is therefore
compatible with other Modbus RTU-capable device series from Bender, such as e. g. the RCMB300
series, RCMS150-01, and RCMB13 ...-01. Up to 247 Modbus-RTU devices can be used on the bus.
The RS-485 specification restricts the cable length to 1200 m and requires a daisy chain connec-
tion.
A A
B B
i
If there are several devices with their own power supply units on the bus, shock-proof-
ness shall be ensured, as the maximum permissible total leakage current of 0.5 mA can
be exceeded.
Termination
The bus line must be terminated at both ends with resistors (120 Ω, > 0.25 W).
A terminating resistor is installed in the device and can be enabled or disabled with the DIP
switch at the underside of the housing.
28 RCMS410_D00424_00_M_XXEN / 09.2022
A
B
max. 1 m
max. 1200 m
A A twisted-pair, shielded cable, shield
on one side to PE, must be used as
B
bus cable. CAT6/CAT7 or J-Y(St)Y
min. 2 x 0.8 are suitable.