Hitachi HIDIC EH-150 User manual

HITACHI PROGRAMMABLE CONTROLLER
RESISTANCE THERMOMETER
INPUT MODULE(EH-PT4)
INSTRUCTION MANUAL
NJI-324(X)

Content
1. Introduction 1-1 to 1-4
1.1 Before Use ·························································································································· 1-2
1.2 Precaution on Use ··············································································································· 1-3
1.3 Features ······························································································································· 1-3
1.4 Principle of Operation ········································································································· 1-4
2.StructureandNameplate 2-1to2-1
2.1 Structure and Name of Each Part ·························································································· 2-1
3.Specification 3-1to3-2
3.1 Specification list ················································································································· 3-1
3.2 Terminal layout and internal circuit······················································································3-2
4.BlockDiagram 4-1to4-1
4.1 Internal Block Diagram .............................................................................................................4-1
5.ExternalWiring 5-1to5-1
5.1 Resistance Temperature Detective Connection Method and External Wiring
············································································································································ 5-1
6.Setting 6-1to6-1
6.1 Setting of Temperature Range ..............................................................................................6-1
7.CollectionofTemperatureData 7-1to7-7
7.1 I/O Allocation ··················································································································· 7-1
7.2 Temperature Data··············································································································· 7-2
7.3 Example of Calculation ······································································································ 7-4
7.4 Correspondence Table between Temperature and Temperature Data ·································· 7-5
8. Error Detection Processing 8-1 to 8-2
8.1 Measured Temperature Range Over···················································································· 8-1
8.2 Treatment for Sudden Change of Temperature Conversion Data········································· 8-2
9.Mounting 9-1to9-2
9.1 Installation······················································································································· 9-1
9.2 Mounting Method··············································································································· 9-1
9.3 Maintenance and Inspection································································································ 9-1
9.4 Precautions on External Wiring ·························································································· 9-2

10.ExampleofProgramming 10-1to10-4
10.1 Example of Programming 1····························································································· 10-1
10.2 Example of Programming 2 (Offset adjustment)······························································ 10-4
11. Troubleshooting 11-1 to 11-1
11.1 The Allocation Error “41” is indicated in CPU································································ 11-1
11.2 Data Error in a Specific Amount ····················································································· 11-1
11.3 Data Error in All Amount································································································ 11-1
12.Appendix 12-1to12-1
12.1 Calculation of External Wiring Resistance······································································ 12-1

1.Introduction
1-1
1 . Introduction
This manual describes how to operate properly the EH-PT4(Temperature detective resistance module),
which is one of the special function module of EH-150 Programmable Logic controller(PLC). Please
read carefully this manual to familiarize yourself with the procedures respectively of installation,
operation, and maintenance and inspection.
Please be sure to read the related application manuals, too.
Table 1.1 Reference Manual list
No. Document Manual No.
1 About the detailed operation method of the programming
unit
1) Instruction word programmer (PGM-CHH)
Instructionwordprogrammermanual
2) Portable indication programmer(PGM-GPH)
Portable indication programmer manual
3) LADDER EDITOR FOR WINDOWS
Programmingmanual
H-PE02-1*
H-PE01-1*
NJI-299*
NB325C*
2 EH-150 application manual NJI-280*
“*” means revision of manual and up to A, B, C in order.
Reference
What is Resistance Thermometer element ?
Measurement principle is based on the property of metals, that the resistance of metals changes
linear depending on the temperature. PT100 is normally used as the metal. (The resistance of
the platinum is 100 Ωat 0 ºC)
Voltage drop of the thermometer element can be measured by supplying a constant current of 1
through 5 mA ( 2 mA in this module) to the resistance thermometer element, and therefore the
temperature can be calculated by the voltage drop.
Use a resistance thermometer element complying with IEC 751 for this module.

1.Introduction
1-2
1.1 Before Use
The resistance thermometer module (Here after EH-PT4) has been carefully manufactured, but you
are kindly advised to make the following checks on receipt of it.
(1) Check whether the module is the right one or not.
(2) Check whether the module was not damaged during transportation.
(3) Check the contents of the package, as below.
The 1.2 Package contents list of EH-PT4 module
No. Contents Quantity Remarks
1 EH-PT4
1
2 I/O cover
1
3 Operation manual 1

1.Introduction
1-3
1.2 Precautions on Use
(1) Before the installation and removal of the module, turn off the power.
(2) Before the connection of the external wiring and removal of the terminal board, turn off
the power.
(3) The terminal board handless fine signals. Therefore upon handling the module or
wiring,
be careful not to apply a voltage on it by mistake or leave it under the influence by
excessive static electricity.
(4) Upon the connection of external wiring, before work, eliminate static electricity by
touching a grounded metal bar to prevent it from being damaged by excessive static
electricity charged on the human body. To prevent a malfunction due to static
electricity
do not touch the terminal during power feeding.
(5) When the connection cable to a resistance thermometer element is cut, the temperature
conversion data becomes abnormal. If the temperature data exceeds the normal
range to protect the external devices, adjust the control system so that the external
devices operate with safety.
(6) If the resistance of a resistance thermometer element (RTD) exceeds 250
ohm(corresponding to about 410ºC ) at PT100, or 2500 ohm(corresponding to about
410ºC ) at PT1000, except when the line is broken, the temperature conversion data is
unstable.
1.3 Features
(1) EH-PT4 applies for two kinds of platinum resistance thermometer elements:
Pt100(IEC 751) and Pt1000.
(2) Temperature measurement range: Three kinds of ranges(selected by switch)
Resistance thermometer
elements Temperature measurement range(ºC) Accuracy(ºC)
Pt100 -50 to + 400 ± 3
Pt100 -20 to + 40 ± 0.5
Pt1000 -50 to + 400 ± 6
(3) Because the accuracy of the temperature measurement range -20 to +40ºC is ±
0.5ºC,EH-PT4 is suitable for exact measurement.
(4) Temperature conversion data: 15 bits with sign.
(5) Number of Inputs: 4 channels, 3-wire system.

1. Introduction
1-4
1.4 Principle of Operation
The EH-PT4 is able to measure the temperature by supplying constant current to PT100/1000 and by measuring
the voltage drop of it, which is based on the linearity between the resistance of PT100 and the temperature. The
operation of the input part of EH-PT4 is shown below.
Fig. 1.4 Principle of Operation
3-wire system
PT100 or PT1000
2mA
The current is very low.
3-wire system
2mA
b3
A3
B3
Voltage
measurement
b0
A0
B0
Voltage
measurement
Constant
current

PT100 or PT1000

2.StructureandNameplate
2-1
2 Structure and Nameplate
2.1 Structure and Name of Each Part
Name and function of
each part
Type EH-PT4
Weight Approx. 180 g
Dimensions(mm)
No. Name Function Remarks
1) Lock button This is used when removing the module from the base
unit. After it is installed to the base unit, the fixation can
be reinforced using screws. In this case, use M4x10mm
screws.
2) I/O cover This is the cover attached to the terminal block area.
3) Terminal block This is the terminal block for connecting input signals. The
terminal block can be connected or disconnected.
4) Setting Switch This is used for setting of temperature range. Refer chapter 6.
Item Detailed explanation Remarks
Operation explanation The module receives input signals from outside. While the
module energized,
The CPU module recognizes the status of the loaded
module and when it matches the I/O assignment
information included in the user program. Input
information is received according to the contents of the user
program.
Terminal block The screws for the terminal block are M3 screws. Use a
crimp terminal that fits the screw diameter. The maximum
thickness of the cable should be only up to 0.75 SQ,
The recommended crimp terminal is indicated below.
 

 
4)
Setting Switch
3) Terminal Block
30 95
100




Un
i
t:m
m

3.Specification
3-1
3. Specification
3.1 Specification list
Table 3.1 shows the specifications of EH-PT4.
Table 3.1 Specification
Item Specification
Type EH-PT4
Resistance temperature detective Platinum resistance thermometer element Pt100
(IEC 751)
Platinum resistance thermometer element Pt1000
Temperature conversion data 15 bits with sign
(In normal state the lowest two bits are always “0”)
Accuracy -20 to + 40 °C (Pt100) ±0.5 °C
(Note 1) -50 to + 400 °C (Pt100) ±3 °C
-50 to + 400 °C (Pt1000) ±6 °C
Temperature measurement range -20 to +40 °C / -50 to +400 °C
(2 mA constant current method)
Number of channels 4 channels
Conversion time Apprx. 1s / 4 channels
Insulation Between channel and PC Photocoupler insulation
Between channels Non-insulation
External power supply 24V DC ±10% 100 mA max.
Internal current consumption
(5 V DC) 200 mA max.
External wiring resistance 400 ohm max. / channel
External wiring Shielded wire
Additional function Linearization
Error detection
-20to+40°C (Pt100)
-50 to +400 °C (Pt100/ Pt1000)
H7FFF is outputted at -25 °C or less, or at +45 °C or higher
H7FFF is outputted at -60 °C or less, or at +410 °C or higher
Processing in case of disconnection
(Note 2) H7FFF is outputted to channel.
Note 1: The above accuracies are the values when 10 minutes after power ON. Just after power ON, the
values may increase slightly. Because a PT100/1000 has a potential error.
Note 2: This is the case when the current terminal wiring is broken. In case the voltage terminal wiring is broken,
the data becomes unspecified. (“H” of “H7FFF” means the following data is hexadecimal.)

3.Specification
3-2
3.2 Terminal layout and internal circuit
Terminal layout Internal circuit
No. Signal name
1) b0
2) B0
3) b1
4) B1
5) b2
6) B2
7) b3
8) B3
9) 24V DC+
10) A0
11) NC
12) A1
13) NC
14) A2
15) NC
16) A3
17) NC
18) 24V DC-
Note 1) Current terminals and a voltage terminals of unused channels should be wired. The data will become H7FFF.



























PT100 IN EH-PT4 PT100/1000 +
+
A0
B0
b
0
A3
B3
b3
Internal
power
circuit
24VDC
24VDC-
Internal current
PT100/1000