Wiring The Modbus Communications Line; Wiring The Input/Output (I/O) Card - Panametrics Sentinel User Manual

1.8.4

Wiring the Modbus Communications Line

The Sentinel uses the RS485 interface with the Modbus communications protocol for a maximum line distance of up
to 4000 ft (1200 m). Panametrics recommends using shielded 22-gauge (22 AWG) cable having a characteristic
impedance of
120 ohms, with a 120 ohm termination at each end of the communications line.
Connect the two leads and the shield of the Modbus line to terminal block J5, slot 2 of the flowmeter., as shown in
Figure 20 on page xxxviii and either Figure 22 on page xl (AC) or Figure 23 on page xli (DC).
1.8.5

Wiring the Input/Output (I/O) Card

The Sentinel can be configured with the following I/O functions:
• Two 0/4 to 20mA isolated outputs, 600
• One frequency (HF) output, optically isolated, from DC to 10 kHz maximum
• One hermetically sealed Form C alarm relay that can be applied to indicate flow direction or fault
• Two isolated 4 to 20mA inputs and 24V loop power for pressure and temperature
• Optional two HF outputs and two alarm outputs or one HF output and 4 to 20mA inputs
Wiring any I/O function requires completion of the following general steps:
1.
Disconnect the main power to the flowmeter and remove the rear cover of enclosure #1.
2. Install a cable clamp in the chosen conduit hole on the top of the electronics enclosure and feed a standard
twisted-pair cable through this conduit hole.
3.
Locate the 12-pin terminal block (J2) in Figure 20 on page xxxviii and wire the I/O terminal as indicated on the
label inside the rear cover (see Figure 13 on page xxvii and Figure 20 on page xxxviii). For wiring diagrams, see
either Figure 22 on page xl (AC) or Figure 23 on page xli (DC).
4. Secure the cable clamp.
WARNING!
5. If wiring of the unit has been completed, reinstall the rear cover on the enclosure and tighten the set screw.
Sentinel™ User's Manual

maximum load
To meet CE Mark requirements, all cables must be installed as described in Appendix A,
CE Mark Compliance.
Chapter 1. Installation
19