External i/o connection, Host ch-0 and ch-1 (bottom), Host ch-0 and ch-1 (top) – JMR electronic Fortra 5251F6 User Manual
Page 17: Ch 2 (bottom), External i/o connection -4, Host ch-0 and ch-1 (bottom) -4, Host ch-0 and ch-1 (top) -4 ch 2 (bottom) -4