Convert number to hexadecimal using Node javascript

I am trying to control a bit of AV equipment using the TCP control API. Here is a screenshot of the command I am trying to build.

This is currently my code:

con = 3017; //0xC9 0x0B
cpu = 1012; //0xF4 0x03
cmd = Buffer.from([
     0x1B,
     0x5B,
     0x49,
     0x09,
     0x00,
     parseInt(con || 0, 10),
     parseInt(cpu || 0, 10)
]);

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My output is:
1B 5B 49 09 00 C9 F4

But I want to get this:
1B 5B 49 09 00 C9 0B F4 03

I think it's because the CON & CPU are 2 bytes, but I don't know how to fix it.

Please can someone help