Hardware Manual

Hardware Manual PCD 1 / PCD 2 Series│Document 26 / 737│Edition EN 15│2008-07-22

Saia-Burgess Controls AG

Storing data in EEPROM

CPUs and expansion housings

3

3.22 Storing data in EEPROM

On the PCD1/PCD2, an EEPROM is used to store configuration data. Part of this is

available to the user to store 32-bit values (EEPROM register). These values are not

lost even in the case of battery failure or an empty buffer capacitor.

On the PCD1 there are five EEPROM registers (addresses 2000 to 2004); on the

PCD2 there are fifty (addresses 2000 to 2049). The EEPROM registers are independ-

ent of the "normal" registers with the same addresses.

The values are read with a SYSRD instruction and written with a SYSWR instruction:

Read: SYSRD K x or R x

R y

; K x is the address of the EEPROM

; register in the range K 2000 to K 2004

; for PCD1 CPUs, or K 2000 to K 2049

; for PCD2 CPUs

; Alternatively, the address of a register

; can also be passed, containing the

; address of the EEPROM register (same

; ranges as for K constants)

; R y is the target register

Write: SYSWR K x or R x

R y

; K x is the address of the EEPROM

; register in the range K 2000 to K 2004

; for PCD1 CPUs, or K 2000 to K 2049

; for PCD2 CPUs

; Alternatively, the address of a register

; can also be passed, containing the

; address of the EEPROM register (same

; ranges as for K constants)

; R y is the source register

When using the instruction SYSWR K 20xx, note the following:

 The EEPROM can be written to a maximum of 100,000 times, so it is not

permissible to invoke the instruction in a cyclic manner or at short intervals

 The processing time for the instruction is approx. 20 ms. For this reason, the

instruction must not be invoked in XOB 0 (XOB for a power outage) or during time-

critical processes