ASCOM T942C User manual

TD 91684GB
16 April 2015 / Ver. G
Installation Guide
T942C and T942C/2 Central Unit

TD 91684GB
16 April 2015 / Ver. G
Installation Guide
T942C and T942C/2 Central Unit
Contents
1 Central Unit T942C ......................................................................................................... 1
1.1 Regulatory Compliance Statements (EU/EFTA only) ...................................................... 2
1.2 Regulatory Compliance Statements (USA only) .............................................................. 2
1.3 Board Description..................................................................................................................... 3
1.4 Installation ................................................................................................................................. 6
1.4.1 Mounting.......................................................................................................................... 6
1.4.2 Opening the Housing.....................................................................................................7
1.4.3 Mounting Together with Other Units........................................................................ 8
1.4.4 Wiring Runs ..................................................................................................................... 9
1.4.5 Addressing.................................................................................................................... 10
1.4.6 Connection of Buses ................................................................................................... 11
1.4.7 Connection of Supply Voltage.................................................................................. 12
1.4.8 Connection of Reference Module in a FL-System (used only in paging systems)
13
1.4.9 Connection of Monitor Input .................................................................................... 13
1.4.10 Connection of PC .......................................................................................................14
1.4.11 Relay Output for System Fault Indication .......................................................... 15
1.4.12 Central Unit Malfunction Output .......................................................................... 15
1.4.13 Activation of Power Changeover Circuit ............................................................. 16
1.5 Installation Test Procedure ................................................................................................. 17
1.6 Circuit Board Replacement.................................................................................................. 18
2 Central Unit T942C/2 ................................................................................................... 19
2.1 General..................................................................................................................................... 19
2.2 Regulatory Compliance Statements................................................................................. 19
2.3 Board Description.................................................................................................................. 20
2.4 Installation .............................................................................................................................. 21
2.4.1 Mounting....................................................................................................................... 21
2.4.2 Opening the Housing.................................................................................................. 21
2.4.3 Mounting Together with Other Units..................................................................... 21
2.4.4 Wiring Runs .................................................................................................................. 21
2.4.5 Connection of Buses ................................................................................................... 22
2.4.6 Connection of Supply Voltage.................................................................................. 22
2.4.7 FLASH PROMs Containing Software for the Main and Communication
Processors ........................................................................................................................ 23
2.5 Installation Test Procedure ................................................................................................. 23
2.6 Circuit Board Replacement.................................................................................................. 23
3 Programming T942C Central Unit............................................................................... 24
3.1 Preparations in PDM ............................................................................................................. 24

TD 91684GB
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Installation Guide
T942C and T942C/2 Central Unit
3.2 Configuration.......................................................................................................................... 24
3.2.1 Set License .................................................................................................................... 25
4 Document History ........................................................................................................ 26

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16 April 2015 / Ver. G
Installation Guide
T942C and T942C/2 Central Unit
1
1 Central Unit T942C
T942C is used in the Ascom Paging System. T942C controls all communication on the
system bus and data buses. The Central Unit also generates code to all H/U952T Terminal
Transmitters and enables parallel operation of separate installations. All the inputs and
outputs have transient protection, and all bus connections are equipped with chokes for
increased EMC protection.
Figure 1. Central Unit T942C.
Supply voltage: 12.5 V DC ±10 %
Current consumption: Max 1 A
IMPORTANT: Protect the unit against current exceeding 20 A. Use power cables with 
cross-section 3 mm2.

NOTE: For 541293A, rev. 3A or later, and T942C2, rev 2A or later: 
Ferrite beads must be mounted on all cables to fulfill EMC regulatory
requirements (see figure 2).
Figure 2. Central Unit with cover removed and ferrite beads mounted on cables.

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Installation Guide
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Delivery includes:
• T942C
• Modular system bus cabling
• FP5 Fuse board 1.25A
Optional equipment that may be required:
• A PC can be connected to 8-pin modular connector J09 on the T942C for RS232C
communication. Adapters can be ordered from Ascom for 9-pin and 25-pin D-sub
connectors. See 1.4.10 Connection of PC on page 15.
Tools, etc., required:
•Screwdriver
• Cutting pliers
• Screws suitable for their purpose (wall-mounting)
• Multi-meter
• Portable Device Manager (PDM)
As a complement to this Installation Guide, see the System Installation document.
1.1 Regulatory Compliance Statements (EU/EFTA only)
Hereby, Ascom (Sweden) AB, declares that this equipment is in compliance with the
essential requirements and other relevant provisions of EMC directive 2004/108/EC.
The declaration of conformity may be consulted at:
https://www.ascom-ws.com/doc/
1.2 Regulatory Compliance Statements (USA only)
FCC Compliance Statements
This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment
generates, uses and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television reception, which can
be determined by turning the equipment off and on, the user is encouraged to try to correct
the interference by one or more of the following measures:
• Reorient or relocate the transmitting antenna.
• Increase the separation between the equipment and Receiver.
• Connect the equipment into an outlet on a circuit different from that to which the
transmitter is connected.
• Consult the dealer or an experienced radio/TV technician for help.

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Installation Guide
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Information to User
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions:
(1) this device may not cause harmful interference, and
(2) this device must accept any interference received, including interference that may cause
undesired operation.
Modifications
Changes or modifications to the equipment not expressly approved by the party responsible
for compliance could void the user's authority to operate the equipment.

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1.3 Board Description
J02J01
J08J07
J14
1 J03 6 1 J04 6 1 J11 6
6
J12
1
SWO1
SWO2
LEDO2
LEDO9
1 3
A
B
S10
1 3
A
B
S17
J13
1
942C
ICO1
IC13
IC14
LEDO1
IC22 ICO8
IC54
IC50
IC56 IC57
IC23
S01
IC20
IC21
S03
S04
S05
S07
S06
S16
S18
S19
S09
S08
BAT1
J09
J05
J06
J10
Figure 3. T942C circuit board.

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T942C and T942C/2 Central Unit
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Connectors
J01, J02: Modular jacks for connection of system bus cabling.
J03: Supply voltage.
J04: For connection of A, C, or D-bus via twisted-pair wiring when modular bus
cabling cannot be used.
J05: Not used.
J06: Not used.
J07: Not used.
J08: Modular jack for connection of A-bus.
J09: Modular jack for connection of PC-line, directly or via modem.
J10: Connector where a relay output is available for system fault indication and
Central Unit malfunction indication. Several parameters in the Central Unit
software determine how the output is to be used. When the Central Unit and
system are operating properly, the relay is actuated, the contacts for the
output close, and LED06 lights steadily.
J11: Connector for 4 external digital 12 V DC inputs. Inputs 2 to 4 are not used.
Input 1 is used for monitor receiver H/U989M.
J12: Connector for 4 external digital outputs (12 V DC) of type open collector.
Output 1 is used only in paging systems for connection of Reference Module
T938RM.
Output 2 (and GND) is used to indicate that the H/U952T Terminal
Transmitter is transmitting.
Output 3 is used to indicate Central Unit malfunction. As long as the Central
Unit is working properly, the output is low.
Output 4 is not used.
J13: Used for diagnostic testing.
J14: Modular jack for connection of D, C, and DR-buses, and AUX RELAY.
Jumper points and push buttons
S01 Push button to manually restart the MP.
S03 2-pin connector, must be jumpered to connect RAM back-up battery.
S04, S18,
S19
Not used.
S05 Not used.
S06, S07 Not used.
S08 Not used.
S09 Not used.
S10A Jumper. Normally must be set to position 1-2 to connect 1 kohm matching
resistor across AUX SP bus.
S10B Jumper. Normally must be set to position 1-2 to select normally closed
contact of AUX RELAY RE02. (2-3 selects normally open contact.)
S16 Not used.
S17A Jumper. Always set to 2-3 to select RS485 for the Ascom Paging System.
S17B Jumper. Always set to 1-2 to select RS485 for the Ascom Paging System.

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Installation Guide
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Switches
SW01 Address selector switch for the C-bus. If the setting of SW1 is changed the
Central Unit must be restarted for the change to become effective.
SW02 If the settings of sections 1, 3 or 4 on switch SW2 are changed, the Central
Unit must be restarted for the change to become effective. Section 1 is set to
ON if a PC (connected to connector J09) equipped with PDM or other special
program, is to be used according to the PC line protocol.
If section 1 is set to OFF, a PC equipped with a terminal emulating program
can be used as an aid at the installation test procedure and for service.
Section 2 is used for test pagings (ON = Test pagings on, OFF = Test pagings
off). Section 2 is normally set to OFF.
Section 3 determines if the parameter list is to be read from the non-volatile
memory or from the FLASH PROM (ON = Read from the non-volatile memory,
OFF = Read from the FLASH PROM). Section 3 is normally set to OFF when the
configuration of parameters is done in PCPAR.
Section 4 determines if the non-volatile memory is to be reset or not after
restarting the Central Unit (ON = Reset, OFF = Reset not). Section 4 is normally
set to OFF.
Sections 5 is used for “off licensed mode”.
Sections 6-8 are not used and are set to OFF.
LEDs
LED01A Green function indicator.
LED01B Red function indicator.
LED02 BCP communication in progress.
LED03 Paging systems: Synch. data transmission in progress on D-bus.
LED04 Communication in progress between MP and BCP.
LED05 Not used.
LED06 Aux. relay output (on connector J10) is active.
LED07 Not used.
LED08 Indicates transmission to external computer (J09).
LED09 Indicates reception from external computer (J09).
IC-Circuits
IC01 Microprocessor, type 80C188EB.
IC08 Module key.
IC13, IC14 FLASH PROMs, contain the software for IC14: the main processor.
IC22 RAM memory with battery backup.
IC54 FLASH PROM, contains the software for the communication processor.

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Installation Guide
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1.4 Installation
T942C should be placed in a dry environment with a temperature range of 0 to +40°C.
1.4.1 Mounting
IMPORTANT: The unit must be mounted by trained personnel.
IMPORTANT: The unit must be mounted to a solid vertical wall with the bottom facing the
floor.
Bottom
Top
The illustration below shows the dimensions in mm for mounting the unit.
9 9
275
56.5
188.5
65 130
112
Dimensions (H x W x D)
275 x 130 x 60 mm
Figure 4. Mounting dimensions in mm.
NOTE: To facilitate service after the unit is installed, we recommend a free space of about
150 mm above and 50 mm below the unit.

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Installation Guide
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1.4.2 Opening the Housing
Use a screwdriver or similar to release the cover by applying a light pressure to the two snap
catches (1) and remove the cover (2).
1
1
2
Figure 5. Releasing the cover.
Opening the Housing from the Front
If the housing has to be mounted without sufficient space below it, the cut-out holes in the
housing lid should be opened to facilitate maintenance.
Cut Out Cut Out
Figure 6. Cut outs for opening the cover.

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Installation Guide
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When the holes are opened, a screwdriver can be used to open the lid. Apply a slight
downward pressure (1), then gently lever the screwdriver downwards (2), the clips which
hold the lid will then be released and the cover can be removed (3).
1
3
2
Figure 7. Removing the cover.
To replace the circuit board, see 1.6 Circuit Board Replacement on page 19.
1.4.3 Mounting Together with Other Units
1
1
Figure 8. Mounting with other units.
1 Remove upper and lower covers. The lower rectangular covers are used to fasten
units to each other (1).
2 Fasten the module with three screws, see 1.4.1 Mounting on page 7.

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Installation Guide
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1.4.4 Wiring Runs
Wiring can be run three ways from the unit:
• Remove the rectangular covers and run the cabling out through the side (1).
• Run the cabling through the round holes at the back of the case (2).
• Remove the circular covers at the top of the side case (3).
1
2
1
2
3
3
IMPORTANT: Do not make any openings at the bottom of the front cover since this does not
comply with the fire enclosure requirements.
The plastic partition is scored to facilitate breaking at convenient intervals.
1 Use pliers to break off a suitable section.
Figure 9. Scored plastic partition for breaking.

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Installation Guide
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2 Run the wiring out through the partition.
1 2 3 4 5 6
1
2
1
Slots
Figure 10. Wiring of modular or twisted pair cabling, 1 and 2.
3 Use the slots at the opening to secure the wiring with cable straps.
1.4.5 Addressing
Assign the T942C an address on the C-bus by setting address switch SW01 hexadecimally.
See the System Installation document, chapter Addressing.
SW01
OFF ON
1
8
Figure 11. Addressing on T942C
• If no additional units are connected to the C-bus: Assign the Central Unit address 00.
• If additional units are connected to the C-bus, the address must not be the same as any
other unit on the C-bus. Note that units on the C-bus must always be assigned addresses
in ascending order starting with 00.

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Installation Guide
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1.4.6 Connection of Buses
Buses are connected either via modular bus cabling or twisted-pairs.
NOTE: The data buses are polarized. Use only twisted-pairs for two-wire connections!
Bus connection via Modular Bus Cabling
See figure 12 on page 12 for information about modular bus connectors.
1 Connect modular bus cabling to J01 and J02.
2 Connect additional modular bus cabling:
J14: connect only the C-bus to another Central Unit via a quick-connect terminal block
(type Krone)
Pin 1
234567
Pin 8
Pin
1
2
3
4
5
6
7
8
Signal
Not used
Not used
Not used
Not used
Not used
Not used
A1 data bus
A2 data bus
J08
Pin
1
2
3
4
5
6
7
8
Signal
C1 data bus
C2 data bus
DR1 data bus
DR2 data bus
D1 data bus
D2 data bus
Aux relay 1
Aux relay 2
J14
Pin
1
2
3
4
5
6
7
8
Signal
A1
A2
B1
B2
D1
D2
Not used
Not used
J01 + J02
Figure 12. Modular connectors J01, J02, J08 and J14.
Bus connection via twisted-pairs
J04
4
5
6
3
1
2
A-bus
D-bus
C-bus
Figure 13. Twisted-pairs connection.
• A-bus to J04 screw 3 and 4.
• C-bus to J04 screw 1 and 2.

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Installation Guide
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1.4.7 Connection of Supply Voltage
1 Add the FP5 Fuse board 1.25A, a very-fast acting (FF) fuse, to the circuit board, in
between connector J03 and the screw terminal.
2 Connect the supply voltage to connector J03 screw 1 and 2.
See the System Installation document, chapter Power Supply.
J03
4
5
6
3
1 +12V
2 GND
Supply voltage in
Supply voltage out
to other units
Supply voltage out to
digital inputs/outputs
Figure 14. Connector J03
NOTE: If the digital inputs and outputs are to be used they must be provided with supply
voltage.
3 Supply the digital inputs and outputs with voltage via connections between J03 and
J11/J12 (see drawing below).
J11
J03
4
5
6
3
1 +12V in
2 GND in
6 GND
1 +12V
J12
6 GND
1 +12V to external
digital outputs
to external
digital inputs
Figure 15. Connection of digital inputs or outputs.
If galvanic isolation is required, remove the connections between J03 J11/J12, and
connect a separate power supply to J11/J12.

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Installation Guide
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1.4.8 Connection of Reference Module in a FL-System (used only in paging systems)
Connect a twisted-pair from connector J12 screw 6 and 2 to Reference Module T938RM
connector J04 screw 5 and 6, respectively (polarized!).
J04
J12
T942C
T938RM
GND 5
REF ON 6
GND 6
1
OUT1 (CODE1) 2
Figure 16. Connection of the Reference Module to the Central Unit.
NOTE: The digital outputs must be provided with supply voltage, see 1.4.7 Connection of
Supply Voltage on page 13.
1.4.9 Connection of Monitor Input
In some cases it may be desirable to prevent the H/U952T Terminal Transmitters from
transmitting, e.g. when a carrier wave is already in the air.
Monitor input can be used to prevent the Central Unit both from activating the output stage
in the transmitters and from sending the transmitter code to them when a carrier wave is in
the air.
Connect a twisted-pair from the monitor source to the Central Unit (connector J11, screws 1
and 2).
J11
4
5
6
3
1 +12V EXT IN
2 IN1
to monitor
Figure 17. Monitor connection.
NOTE: The digital inputs must be provided with supply voltage, see 1.4.7 Connection of
Supply Voltage on page 13.

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Installation Guide
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1.4.10 Connection of PC
The serial communication port on the PC is to be connected to 8-pin modular connector J09
on the T942C, either directly or via modems. (See the drawings below.)
1 (not used)
2 TX
3 RX
4 (not used)
5 (not used)
6 (not used)
J09
7 GND
8 (not used)
1
RX 2
TX 3
4
GND 5
6
7
8
9
T942C
9-pin female
D-subconnector
for direct
connection
to PC
Figure 18. 9-pin modular connector.
1 (not used)
2 TX
3 RX
4 CTRL IN
5 CTRL OUT
6 (not used)
J09
7 GND
8 (not used)
1
TX 2
RX 3
RTS 4
CTS 5
6
25-pin male
D-subconnector
for connection
to PC via
modem
GND 7
DCD 8
DTR 20
T942C
25
Figure 19. 25-pin modular connector.
NOTE: Note that on modems with 25-pin D-sub connectors, the RTS and CTS signals must be
jumpered - i.e. pin 4 to 5.
Adapters with the correct connections can be ordered from Ascom for both the 9-pin and
25-pin D-sub connectors.

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Installation Guide
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1.4.11 Relay Output for System Fault Indication
A relay output on connector J10 is used to indicate Central Unit malfunction and can also be
used to indicate system fault (e.g. system fault can be when a module drops out or reports
an error). Several parameters in the Central Unit software determine how the output is to be
used.
2
1
J10
T942C
RE02
321
S10B
Aux relay output
Figure 20. Relay output connector.
If the relay output is set to indicate system fault it is possible to use output 3 on connector
J12 to indicate Central Unit malfunction only, see the next section 1.4.12 Central Unit
Malfunction Output on page 16.
As long as the Central Unit and system are operating properly the relay is actuated and has
a make-function.
NOTE: At power-up or restart of the Central Unit the relay is deactuated for about 20
seconds. If the relay is deactuated for more than 20 seconds either the Central Unit or
system is malfunctioning.
1.4.12 Central Unit Malfunction Output
If the relay output on connector J10 is used to indicate both Central Unit malfunction and
system fault then output 3 on connector J12 (screw 4) can be used to indicate Central Unit
malfunction only.
J12
4 OUT3
5 OUT4
6 GND EXT
3 OUT2 (CODE2)
1 +12V EXT OUT (CODE+)
2 OUT1 (CODE1)
Max load
100 mA
T942C
Figure 21. Connection of Central Unit malfunction only on pin 3 on J12.
The output capacity is max 100 mA and is of open collector-type, which means that to
produce a digital 12V signal a resistor must be connected between the output and +12V
(screw 1). If a digital signal is not wanted a relay can be connected between the output and
+12V.
As long as the Central Unit is operating properly the output is actuated.
NOTE: At power-up or restart of the Central Unit, the output is deactuated for about 20
seconds. If the output is deactuated for more than 20 seconds the Central Unit is
malfunctioning.

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Installation Guide
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1.4.13 Activation of Power Changeover Circuit
Activate the RAM back-up battery by closing jumper S03 on the circuit board.
S03
BAT1
Figure 22. The RAM back-up battery.
NOTE: The power changeover circuit contains a 3V lithium battery. At any interruption in the
ordinary +5V supply, both the RAM and real-time clock will be supplied by the battery
so that they retain their data.
Data
Current consumption, RAM and real-time clock:
• 3 V battery: typical 2 µA, max 40 µA
Battery life (battery connected):
• 5 V not connected: typical 7 years, min. 0.5 years
• 5 V connected: minimum 10 years
Battery life (battery not connected):
• min. 10 years