K-Patents PR-03 - Manual (Page 19)

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3 Indicating transmitter (IT-R) 13
symbol. The connection is made by inserting each lead into the corresponding slot and tightening the screws
above the slots (Figure 3.7).
The ground terminal (41) is connected to the bottom plate of the Indicating transmitter, to the transformer
shield winding and to the outer shield of the interconnecting cable.
Important: The power selector switch on the Power supply card, marked SW2, must be in 110 position
(Figure 3.9) when input voltage is +24 V DC. If the switch is in the wrong position, the refractometer system
does not work.
Figure 3.9 Power selector switch in the 110 V +24 V DC position
3.2.2.4 Current output connection
The current output connection terminals are 25 and 26. The terminal 25 is plus (+) and 26 minus (-) for the
4-20 mA output signal (The detailed signal specifications are listed in Section 9.4, “IT-R Specifications”).
Recorders, controllers, indicators etc. must be connected to form a closed current loop, starting from termi-
nal 25 passing each device, in at plus and out at minus, ending at terminal 26.
Important: Be careful not to exceed the specified load resistance, 1800 Ohm.
3.2.2.5 Serial bus connections
Terminals 8-14 on the Power supply card provide connection to K-Patents accessory units, like a Relay Unit
(see Section 4.1) and External output unit (see Section 4.2). The connection cable is of the same type as the
interconnecting cable and follows the same specifications (see Section 9.4). See Section 4.1.3, “Relay unit
mounting and connections” and Section 4.2.2, “External output unit mounting and connections” for more
information.
3.2.2.6 Input switch connections
Altogether four input switches A, B, C and D can be connected: Terminals 27-A, 28-B, 29-C, 30-D, 31-
Common, Figure 3.10. To use a switch, you will have to connect that switch with terminal 31, which short
circuits that switch. Thus, to use switch A, connect terminal 27 with terminal 31.
The switches may be separate, or together in one rotary switch. Input switch functions are configured
through software, Section 5.6. Most commonly input switches are used for easy switching between calibra-
tion settings for different process mediums or for preventing accidental or unauthorized calibration changes.
A 5V voltage is provided over each switch. The switch terminals are all galvanically isolated from ground
and from the rest of the electronics.