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TVP Manual (full) March 2007 CE rev 03.doc
4.20 Interfacing to the TVP
The TVP is supplied as standard with a remote interface; connection is via an industry
standard 37 pin AMP plug
Diagram 20 AMP style 37 pin connector - connector side
The User Interface is automatically enabled when pin 9 is connected to system GND (pin
24); this link is installed in the supplied connector.
When the connector is inserted, the system switches to REMOTE - indicated on the top left of
the LCD display. In REMOTE only the “SCROLL” key functions, but all the indicators continue
to function (i.e. COOL, DEFROST, STANDBY) along with the RS232 read commands (includes
logging).
The system can only be taken out of remote by either removing the connector or by selecting
RS232 control via the serial link.
All the remote indicators function at all times regardless of system status i.e. The system can
be in LOCAL or RS232.
4.21 Digital Inputs
The digital inputs accept an input voltage with a digital threshold at ~ 2.5 volts. The inputs are
protected against overload over a range from –48 to + 48 volts. These inputs are useful for
detecting contact closures or sensing devices with open collector transistor outputs, logic level
outputs can also be detected as long as they are from a CMOS logic output guaranteed to
swing at least 3.5 volts.
The input has an RC circuit with a 0.2-millisecond time constant to stabilize signals, signals
faster than 5khz can be effected.
4.22 Digital Outputs
The digital outputs are fully isolated, they provide a contact closure to ground rated for up to
1A @ 24 VAC. The commons are all linked for the user to connect to ground or apply a
voltage (pins 4,6,17,29), a 24 VAC source fused at 2A is provided on pins 35 & 36 to drive
external relays.
Suggested Wiring Schemes
DWG PB200204-1 Suggested interface schematics.pdf
Note the term Low = Closed or connected to gnd
Caution
Interface is fully isolated the indicated GND (ground) is not earth connecting return side of
operate relays will induce control errors.
Within the 37-pin remote interface plug supplied with the unit. For your convenience the link
between pins 9 and 24 is made this has the effect of automatically forcing the unit into remote
mode when ever the interface plug is connected. If the interface plug is to be used purely for
data logging the analog output this link must be removed.
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