Problem using ICSC (by majenkotech) in RS485 bus
The documentation for the constructors is out of date (I am re-writing as we speak, and is now here).

The constructors in the header file are like this:

ICSC(Stream *d, uint8_t station);
ICSC(Stream &amp;d, uint8_t station);
ICSC(Stream *d, uint8_t station, int depin);
ICSC(Stream &amp;d, uint8_t station, int depin);


That means you need to provide the serial object as the first entry:

ICSC icsc(Serial1, 'A', 5);


You need to manually start the serial object before ICSC.

void setup() {
    Serial1.begin(9600);
    icsc.begin();
}


This change was made to enable support for software serial and other Stream based devices.



Addendum for your update:


Don't spam the sending like you are. Send periodically, not constantly, or you will never be able to receive.
You cannot use String objects like that. 
1 and 2 aren't good choices of station IDs. Yes, they work, but not great, since 1 is the SOH character.