.json in Ionic 2

Hello! I’m working in one application in Ionic 2 and I’m connecting it with node.js server. For send data (server - Ionic) I send like this:

http.createServer(function (req, res){

res.end(data); // data is 0 or 1
In Ionic, I get the data like this:

this.http.post(“”, ‘PidoDatosClima’ + ‘_’ + this.parameter1)
.subscribe(data => {

Where resp is 0 or 1 so… in this example work fine.

My problem is when I need to send more data in my server so… if in “res.end(data)” data is the string “1_2_3”

In Ionic, I get this error: “EXCEPTION: SyntaxError: Unexpected token _ in JSON at position 1”

Somebody know how can I solve it? Thanks in advance.

Best regards.