Oxford Instruments Mercury iTC, Handbook

Page: 61 / 146

Handbook
November 2011 / 59-UMC0071 / Issue 01
Mercury iTC
Page 61
FUNCTIONAL DESCRIPTION
Original Instructions
The iTC uses a PID loop to control each heater (see Chapter 12 for information on PID
loops). The control system includes a dead-man’s-handle timer to confirm that the
control loop is operating. If the control loop stalls, the heater output is disabled.
4.2.4 Heater and sensor connections
The heater and sensor are connected via a 9-way D-socket on the rear panel.
Connections to the sensor vary depending on the type of sensor in use (see Table 4-2 ).
4.2.4.1 Connecting thermocouples
Thermocouples must be connected using the correct wire type to ensure measurement
accuracy.
4.2.5 Communications interfaces
Connectors for the communications interfaces are located on the rear panel of the iTC.
The unit has the following interfaces:

Serial RS232 + ISOBUS (see Section 4.2.5.1 )

Serial2 USB (see Section 4.2.5.3 )

GPIB (IEEE-488) (optional) (see Chapter 17 )

Ethernet 10/100 IEE802.3 (see Section 4.2.5.4 )
Table 4-1 Channel pin connections
Pin
Number
Connection
1 Sensor input high
2 Sensor input screen.
3 Sensor input low
4 Current ve
5 Current source -ve
6 Heater ve
7 Heater output -ve
8 Not used
9 Chassis ground.
Table 4-2 Sensor connections
Connection Thermocouple Metal Resistor Ge/Carbon
Resistor
Si/Ga As Diode
Input High V+ V+ V- V-
Input Low V- V- V+ V+
Cve n/c I+ I+ I+
Current -ve n/c I- I- I-