Modbus Network Configuration - Emerson MRLDS-250 Installation And Operation Manual

Figure 3-5 - Sample Relay Output Wiring
NOTE: The relay can be
programmed to be failsafe
(normally energized). By default,
the relay is set to be normally
de-energized. This can be set using
parameter P-06.
Make relay connections (NO, NC, or both) using 18 to
20 AWG wires to terminal block positions 10, 11, and
12 (see Figure 3-5), noting normally open, normally
closed, and common connectors per Table 3-3.
Function Pin
10
Relay (Alarm)
11
Output
12
Table 3-3 - Relay Output Terminal Block Connections

MODBUS Network Configuration

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Mounting
Procedure
Relay NC contact
Relay common
contact
Relay NO contact
3.5. MODBUS Network
Configuration
If your application includes a MODBUS network,
make network connections (RS-485 A and RS-485 B)
using 18 to 24 AWG shielded twisted pair wires (with
120 ohm characteristic impedance) to terminal block
positions 7 and 8 Figure 3-6 noting inverted B (-) and
non-inverted A (+) signal connectors per Table 3-4.
Figure 3-6 - MODBUS Network Wiring
Function
MODBUS
Network
Communications
Table 3-4 - MODBUS Network Communications
Connections
CAUTION: For MODBUS network
communications wiring, use only
18-24 AWG shielded twisted pair wire
with 120 ohm characteristic
impedance.
Wiring
Pin
Termination
7 RS-485 "B" (inverted)
8 RS-485 "A"
(non-inverted)
9 RS-485 shield
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Wiring and Configuration • 11
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