Here is the simple code:

' ************************************************** ************************
' Programme: Test SEROUT.PBP
' RGL 02-2022
' Testing AXE134 (Picaxe 4x20# OLED Display) ---> PIC 16F630
' PicBasicPro Compiler V:2.40
' ************************************************** ************************


Include "modedefs.bas"

' Pic Specifications
'--------------------
'PIC16F630 with 16Mhz resonator
@ Device Pic16F630,HS_OSC, WDT_OFF, PWRT_ON, PROTECT_OFF, MCLR_OFF
CMCON = 7 'Deactive Comparator RA0+, RA1-, RA2 out
DEFINE OSC 16
DEFINE CHAR_PACING 500

' ******* VARIABLES / CONSTANTS **************************
Symbol BAUD = N2400
Symbol OLED = PORTA.0 'pin13

'*** Definition i/o
'All OUTPUT
TRISA = 0
TRISC = 0

Pause 1000

Serout OLED, BAUD,[254,1] : pause 30 ' Clear Display
Serout OLED, BAUD,[254,128] : PAuse 30 ' Line1, Col1

LOOP:
Serout OLED, BAUD, ["UUU"]
Pause 1000
Goto Loop