converting cencal protocol to modbus

  • Thread starter Jose Ricardo Pabon
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Thread Starter

Jose Ricardo Pabon

I need to connect 16 gefran controllers to a modbus network using a momentum PLC. The gefran controllers support the cencal protocol.

Anyone knows how to convert the cencal protocol to modbus protocol? Is it possible using a momentum PLC?

Robert Willis

It all depends on the specifics of the cencal protocol. Do you have some information on the details of this protocol?

Robert Willis
Square D Company
Houston, Texas
E-Mail: [email protected]
I contacted Gefran and asked for info on the protocol. After swearing an oath of secrecy you get a copy of the protocol, such as it is. A
word of warning, you need to be able to do some odd things with the parity while you communicate with the controllers and windows (taking a
stab in the dark here) typically does not like this.

I have looked at doing a microprocessor based convertor but have not gone further because I can't see a huge demand for one - what do you

Steve B.

Oscar Milanese

Consulting the Gefran internet site and calling the help desk I can confirm you what follow
1)CENCAL is an old proprietary protocol made by Gefran (CENtro di CALcolo)for controllers
2) the new range of controllers (model 800, 1600, 1800) has 2 protocols : Cencal and Modbus,
you can use one.
2)unfortunaly it does not exist a protocol converter CENCAL / MODBUS, so I suggest you some
possible solution :
a)verify if the controllers have 2 protocols, then you can change the protocol
b)else, change the old controllers with a new one
c)you must build a converter: in this case you cannot use a Momentum PLC. You should use a
BM85S232 (1 MBus + 4 open RS232) or a TSX Micro / Premium PLC with RS232 or 485 PCMCIA card.
In this case I suggest you to contact Gefran technical support to have the specifications of
Cencal. They have an Agency near BOSTON (Gefran Easy, Winchester, Mr. TOMLINSON, tel 001 781
7295249, e-mail [email protected]) or calling the Italian head Quarter in Brescia (Mr ARMANDO LENZA tel +39 030 9888321).
Best Regards
Oscar Milanese

Jose Ricardo Pabon

Thanks for your answer. The serie 1000 controller only support the cencal protocol. I will contact to Gefran to know if it is possible to upgrade the
serial protocol.

I don´t understand How i could use a TSX micro to convert the protocol? Can i built a custom serial protocol in ascii mode.?


Mark Harrison (Gefran CRL Ltd) - UK

Many Gefran controllers and panel meters are now available with Modbus comms as an option. I have one in my demo case.
Gefran now also have a range called ALLEX which is "blind" controllers and heat sinked SSR in one unit. These communicate with an HMI on Modbus. [email protected]