MODBUS INSTALLATION
Part. No. 2400M2501_6 Touchpoint Pro
34 Technical Handbook
5.1.4 DC Power Output
The TPPR DC power output can be set to between 24 and 28 VDC (the default is 24 V).
TPPR power supply units (PSU) include a DC Ok relay that closes when the output voltage reaches the adjusted output
voltage level, and opens when the output voltage dips more than 10% below the adjusted output voltage level.
The DC Ok Relay has a maximum rating of 60 VDC 0.3 A, 30 VDC 1 A or 30 VAC 0.5 A resistive load and a minimum
permissible load of 1 mA at 5 VDC.
Note: If the battery backup option is being used, ensure that the PSU DC output and the DC-UPS Module buffer voltages
are set to >24 V to ensure optimum battery charging for 2 x 12 V batteries.
Note: If the Power Redundancy Module is being used, ensure that both PSUs have the same output voltage.
5.2 Cabling Requirements
All cabling should meet local, national and international regulations, and be suitable for the operating environment. Cable
should be appropriately rated and approved. Bootlace ferrules should be used on all stranded cable end terminations unless
otherwise stipulated (e.g. where the backup batteries use spade terminals).
5.2.1 Device Cables
Field device cabling should be appropriate to the area classification, and in accordance with the device manufacturer’s
recommendations. Refer to local and national regulations where appropriate, and the field device manual. All sensor field
cables must be shielded and grounded to ensure correct operation of the system and to meet European Standards for RFI
and EMC.
Ensure that the maximum loop resistance is not exceeded, as specified by the device manufacturer.
Take account of voltage drops due to line resistance to ensure that the correct voltage level is present at the field device, as
specified by the device manufacturer.
The I/O modules will accept wire sizes up to 2.5 mm² / AWG 11.
5.2.2 External Power Supply Cables
Use approved supply cables rated in accordance with the rating plate on the specific system, in accordance with local and
national regulations. The TPPR power supplies will accept wire sizes in the range 0.5 – 6 mm² / AWG 25 – 3 (solid wire), 0.5
– 4 mm² / AWG 25 – 7 (stranded wire).
5.2.3 Bus Interface Cables
Modbus cables should use a good quality signal cable suitable for RS485 connections. See Ch.6.5 Modbus Cables for
further information.
In Canada and the USA, in both ordinary and hazardous locations, all electrical installations, including connections,
cabling and overcurrent protection must strictly adhere to both the National Electrical Code (NEC) and the Canadian
WARNING
All cabling must be appropriately rated and approved in accordance with local, national and international regulations.
Additionally, cabling must satisfy requirements defined in the technical manuals of connected field devices,
especially when the field device is certified for use in hazardous locations.
This is particularly important when reusing existing or legacy cables.
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