IM-P192-02 MI Issue 2 43
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Th e c o m muni c at i on s p roto c o l has b een s e t up o n t h e c o mmu n i c a t ing d e v i c e as d e sc r ib e d
earlier in this Section. The following is a Table of operating codes in ASCII characters:-
ASCII communications
Please note that all the following commands are case sensitive…
User transmits TVA responds (metric) TVA responds (imperial)
AB[LF] Pressure in bar g [LF] Pressure in psi g
AC[LF] Line Temperature in °C [LF] Line temperature in °F
AH[LF] Energy total in kWh [LF] Energy total in kBtu
AP[LF] Power in kW [LF] Power in kBtu / h
AR[LF] Flow rate in kg / h [LF] Flow rate in lb / h
AT[LF] Total in kg [LF] Total in lb
4.12.3 Using RS485 Communications
The TVA is available with RS485 communications. This is achieved by converting the
communication from RS232 by an additional PCB. The PCB is fitted at the factory when the
TVA is ordered with RS485 communications.
However, the RS485 communications board is available if ordered with a replacement
electronics front panel.
Note: RS232/4-20mA outputs are not available if the RS485 board is fitted.
The TVA is a RS485 slave device and must be powered by connecting 24VDC to terminals
4 and 5.
The data terminals are 1-3 and all must be connected for the communication to work correctly.
Terminal Signal
1 Data +
2 Data -
3 Data GND
4 Power +
5 Power -
4.13
After installation or maintenance ensure that the system is fully functioning.
Carry out tests on any alarms or protective devices.
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