Chapter 2 Getting started
Page 2.14
2.8 Example 5: 7951 with a PRT-type temperature transmitter
About this example
This example shows you how to connect a PT100 transmitter to the 7951, and then use the “Temperature”
wizard to configure the system.
In this example, the “Temperature” wizard is used to configure a connection as follows:
x A single PT100 transmitter is connected to Analogue Input 1.
Work through the example by following the instructions below. If you are not sure where the buttons are, refer to
Chapter 6.
Connect the
meter
1. Wire the transmitter to the 7951, as in Figure 2.14.
2. Earth the 7951 to a suitable earth point.
EMC Notes:
To meet the EC Directive for EMC (Electromagnetic Compatibility), it is recommended that
the Flow Computer be connected to transducers using a suitable instrumentation cable
containing individually shielded twisted pairs and an overall screen to cover all cores.
The instrumentation cables should have individual screen(s), foil or braid over each
twisted pair and an overall screen to cover all cores. Where permissible, and depending on
the earthing scheme employed at the installation, the overall screen should be connected to
the earthed metal work at both ends (360° bonding where possible). This may have multiple
protective earth connections to the pipe work or the building structure and not connected to
the individual screen(s) or Instrumentation or Zener barrier grounds.
The individual inner screen(s) should be connected at one end only, normally the controller
(e.g. Flow Computer) end. These should be connected to the Instrumentation or Zener
barrier ground.
Use suitable cables that meet BS5308 multi-pair Instrumentation Types 1 or 2.
Set DIP switch 3. Set DIP-switch position 1 to “PRT” (for Analogue input 1).
PT100 on
Analogue
Input 1
Signal +
Signal -
Power +
Klippon D-type
PL7/1
PL7/2
PL7/3
PL7/4
SK7/14
SK7/15
SK7/16
SK7/17
7951
Power -
PRT
Notes:
1. Specified 7951 pins are for Analogue Input 1.
2. DIP-switch position 1 must be set to PRT.
D
C
B
A
4
3
2
1
4-20mA PRT
Figure 2.14: DIP switch and safe area wiring for a PRT-type temperature transmitter