You had me wondering about the difference between the 2
So I opened up my cable to check it out I made up my cables about 30 years ago been using then since.
To answer your question you cannot use the SLC 100 programming cable to program the PLC2’s
While both are RS422 the PLC2 requires 4 channels RD, TD, RTS, CTS the SCL only requires
2 channels TD, RD
On RS422 each cannel is 2 wires +, -
The SCL port supplied 12VDC power to the converter with the PLC2 the converter must have an external power supply
The converters I have are B&B 8 channels and I understand they have been obsolete for a number of years there was a replacement available that would work up until recently, 422CEC
I just checked it is no longer available
So you are right the programming cable is the problem now.
There is a backdoor to program the PLC2’s Over the Data Highway
PLC2 - Data Highway module - Data Highway to RS232 module I have used this a few times where it was available.
A note here Data Highway and Data Highway Plus are not the same thing and should not be confused