Manufacturer Part Number

Specifications of EA-IF-E2

No SVHC (18-Jun-2010)
Accessory Type
Interface Card
Engineering Laboratory And Complex Industrial Application
Approval Bodies
Rohs Compliant
For Use With
EA Elektro-Automatik PSU
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
About the interface cards
© 009, Elektro-Automatik GmbH & Co. KG
The implementation of the VCP driver is easier, but this
driver is more susceptible to communication problems and
errors. It also creates a new COM port for every USB card,
which complicates the port management. The USB driver
requires the user to create own routines, which handle the
USB low level communication, in order to ensure the proper
transport of the communication data of our system. These
routines are not offered by us. Sample code is available on
the web site of the manufacturer FTDI, at www.ftdichip.com.
The USB chip is named FT3B
7.5 Structure of the communication
The communication with the controlled units is based on
these telegram types:
a) Simple message: an object is sent, which shall for instance
set the output voltage. As long as this action is permitted by
the current state of the device, the object is accepted and
executed. The device won’t send any answer. If it’s not per-
mitted it will send an answer, an error message.
b) Query: a query is sent by using a certain object, for in-
stance „get actual values“, and an answer is expected. If
the query is permitted for the current state of the device it
is executed and answered. The answer contains the reque-
sted data. If not permitted it will send an error message as
c) Event: is an error message, which is sent by the device
without request, for example if the access to an object is not
permitted or if the previous message was not recognized by
any reason, like if it was crippled by external interferences.
Contains an error code.
7.6 Transmission settings IF-R1 and IF-U1
At the serial transmission of one byte with the RS3 card
following bits are sent:
Start bit + 8 Data bits + Parity bit + Stop bit
The parity is checked for „odd“.
The USB card is internally working with the RS3 charac-
teristic For both card types it is required to set at least these
transmission parameters for the particular driver:
7.7 Translating set/actual values
The set values and actual values (see communication object
list) are, with a few exceptions, transmitted as percentage
values, whereas 0x6400 corresponds to 100%. If a device
has a nominal voltage of 80V and the queried actual value
is 0x300 (0x3 = 50 = 50%) then it corresponds to 40V
output voltage.
The high byte is the percentage number (0x64 = decimal
100) and the low byte is the decimal place of it. You need to
translate the outgoing set values and the incoming actual
values before they can be used.
Baud rate:
Stop bits:
9600Bd-57600Bd (56700Bd only for USB)
Example: Nom. value of the device is 80V, the percentage actual value
came in as 0x454 = 9300. It results in: Actual value = (80 * 9300) /
5600 = 9.06V
Example: the set value for voltage shall be 5.36V, the nom. value of the
device is 80V. With the formula it results in:
Percentage set value = (5600 * 5.36) / 80 = 8115 = 0x1FB3.
You need to, of course, round the decimal value for the hex value.
7.8 Telegram structure IF-R1 and IF-U1
The interface cards IF-R1 and IF-U1 are using the same te-
legram structure, the one of the CAN card IF-C1 is different.
Read below if you‘re using a IF-C1 card.
The telegram is structured like this
and is built by these bytes:
Byte 0: SD (start delimiter)
The start delimiter determines how to handle the telegram
furthermore. Meaning of the bits:
Byte 1: DN (device node)
The device node identifies and adresses devices inside a bus
system. Each node number must only be assigned once. This
is used to address a particular device. Value range: 1...30,
others are invalid. Using CAN, the CAN ID is calculated from
the device node. See section 7.9 for details.
Byte : OBJ
The communication objects for a device are addressed by
this byte. In the communication object list (see section 9.3)
the objects and their function(s) are explained in detail.
Bits 0-3: Data length (Bytes 3-18)
Bit 4
Bit 5
Bits 6+7: Transmission type
Actual value =
Define the data length - 1 of the data in the telegram. At a
query the data length of the expected data is given here.
Percentage set value =
0= Telegram from device to control unit
1= Telegram from control unit to device
0= Singlecast, telegram to a certain device node
1= Broadcast/Multicast, telegram to all device nodes
00 = Reserved
01 = Query data
10 = Answer to a query
11 = Send data (without previous request)*
* can also occur from the device
Nom. value * Percentage act. value
Nom. value of the device
5600 * Set value

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