EVCO S.p.A.
EVDRIVE04 | User manual ver. 1.0 | Code 144EPD4I104
Page 57 of 78
8
SERIAL COMMUNICATION
8.1
Preliminary information
It is possible to control the EVDRIVE04 driver by connecting it to a controller.
The controller sends information to the driver necessary for its correct functioning, and the driver responds with its
internal states, such as (for example) the pressure and temperature measurements, alarms, certain parameters, etc.
The connection methods available on the EVDRIVE04 are CANBUS, MODBUS RS-485 and MODBUS USB, according to
the model.
The protocol to be used for communication with the controller must be selected via parameter Enabling mode (Pr06).
See the “Enable EVDRIVE04” section.
The EVDRIVE04 behaves as an expansion to read the analog inputs AI1 and AI2, read digital inputs and write the relay.
(Note that driving the relay by the controller completely bypasses its function set by parameter.)
8.2
CANBUS serial communication
The EVCO controllers primarily use a protocol based on CANbus for communication with controllable systems.
8.2.1
CAN Master tool
The exchange of data is based on a list of variables or parameters that the controller may send to the driver, and a list
of variables the driver sends to the controller to provide its state data, using the CAN Master tool.
The variables and parameters to be monitored should be selected from lists proposed by SW development according to
their own needs.
The protocol performs one send request every second and one receive request every second, which does not occur
simultaneously. Each send/receive request is done on a different node, thru the nodes on the network.
You can give a different timing of the individual entities. The levels selected are:
•
Level INIT: the value is written (or read) only once when the controller detects a new node in the network. If
the node is disconnected and then reconnected the initialization is done again.
•
Level LO: every 10 seconds is written (or read) one of the entities with this priority.
•
Level HI: each 1 second is written (or read) one of the entities with this priority.
When you connect a device to the network, the controller read and write all entities without differentiating the
priorities. Once this step is completed for each node, entities with priority INIT will no longer be requested.
The refresh time of the single entity depends, therefore, both on its level and on the number of entities of the same
level and type (read / write).
8.2.1.1
Status variables
AI1 type (AI1T used if Piu1 = 0)
AI2 type (AI2T used if Piu1 = 0)
Ai error timeout
FSM status
(Stat)
Used SH control parameters set
(SetS)
Measured SH
(SH)
Used SH set-point
(SpSH)
Measured aspiration temperature
(Ts)
Measured evaporator pressure
(Pe)
Calculated evaporator temperature
(Te)
Unit uf measure in use
(UdM)
Working hour
(Pr40)
Control algorithm status
(AlgS)
Alarm status
(AlSt)
Configuration warning
(CoWa)
Enable valve status
(EnaS)
Request a reset status
(ParS)
Resynchro request status
(ResS)
